Annual cultural practice for peach

Savvas Pastopoulos, Agronomist MSc, Pastopoulos Agronomics

Peach belongs to the stone fruits, and it is the most difficult and the most demanding of them to grow. The steps that decide whether it succeeds are the right choice of cultivars and a thorough command of crop protection, fertilisation and irrigation. This manual sets out the basic practices season by season.

Rates are given per hectare The Greek edition of this article works in stremmata, the unit used on Greek holdings. Here every rate has been recalculated per hectare: 1 ha = 10 stremmata. Rates expressed per hectolitre of spray solution, per tree or per tonne of fruit are unchanged, because they do not depend on area.

Contents

The essentials of the crop
Table 1. Suggested sprays by phenological stage
Peach leaf curl, the disease with a single window
Fertilisation of peach
Table 2. Suggested fertiliser programmes
After harvest
Sources

How this text is read The numbers in square brackets refer to the list of sources at the end. Where a figure comes from a foreign trial, the country and the species are stated inside the sentence, because dates, insect generations and thresholds do not transfer unchanged to Greek conditions. Where no published measurement was found, that is stated explicitly instead of being filled in with an estimate.

1. The essentials of the crop

The cultivars to be planted must suit the soil and climate of the district. Peach prefers deep, fertile soils with good drainage.

Resistance to Sharka, a correction that is needed

The recommendation to “choose cultivars resistant to Sharka” is often repeated, but in peach no commercial resistance is available. The EPPO database for plum pox virus (Potyvirus plumpoxi) states that “the development of resistant peach varieties remains a challenge due to the scarcity of resistance sources”, in contrast to apricot, where cultivars resistant to the PPV-D strain are already grown extensively in parts of Spain [17].

The virus is recorded in mainland Greece. The defence rests on certified, virus-free propagation material and on the removal of infected trees to reduce inoculum. Aphid control with aphicides or summer oils has, according to the same source, “only limited efficacy”, with nurseries a possible exception, because transmission is non-persistent and takes place before the insecticide can act [17].

What the irrigation method changes

Peach is irrigated by drip or by microsprinklers under the canopy. Flood or furrow irrigation creates exactly the condition that Phytophthora needs: according to the University of California guidelines for peach, periods of soil saturation of 24 hours or more favour Phytophthora infections, while good drainage and more frequent but shorter irrigations reduce the risk of root and crown rot. No rootstock is resistant to every pathogenic species of the genus [9].

For the same reason, wetting the fruit from above is avoided. The same source notes, for shot hole, that “summer rain or sprinkler irrigation favours fruit infection”, and that the attack is heavier low in the tree, where the fruit stays wet for longer [7]. The same logic applies to brown rot of ripe fruit, where wetting by rain or dew increases preharvest infection [5].

Sources: 5 7 9 17

2. Table 1. Suggested sprays by phenological stage

Why stages and not months The University of California programmes for peach are not organised by month but by phenological stage: dormancy, 20 to 40% bloom, 80 to 100% bloom, 3 to 6 weeks after bloom, 3 weeks before harvest and 1 week before harvest [6]. The months that follow are indicative for the plain of Central Macedonia and shift from year to year and from cultivar to cultivar; what is binding is the stage.

Dormancy, January and February

Sprays with copper products against peach leaf curl and shot hole. In the California guidelines the shot hole spray is placed “at leaf fall, or from 15 November to 1 December, before the winter rains”, so that twig infections are prevented [7], while for leaf curl an application is foreseen “in late November to early December, once most of the leaves have fallen”, with an additional treatment in January or early February if December and January rainfall is high [1].
A correction regarding bacterial canker. Dormant copper is often cited as a measure against bacterial canker of stone fruit. The California guidelines for peach say the opposite, explicitly: “Dormant copper application is not effective against bacterial canker”. Management there rests on keeping the tree tolerant rather than on killing the bacterium: rootstock choice, correction of vigour through irrigation and nutrition, and control of the ring nematode Mesocriconema, with which disease severity is strongly correlated [8].
Sprays with calcium polysulphide (lime sulphur) on holdings with a history of scale insects. Lime sulphur is among the products that the Pacific Northwest handbook lists for peach leaf curl [3]. For San Jose scale, the California guidelines place the treatment in the dormant period with summer oil, when populations are low to moderate [10].
Zinc. Where a deficiency has been established, the application is made as a spray and not to the soil. Washington State University notes that “on high pH soils, soil zinc correlates poorly with tree status” and that “on high pH soils, regular maintenance zinc sprays are recommended” [22]. The soil application rate that circulated in an earlier form of this text has been removed, because it is not documented and points to the wrong route of application for the calcareous soils of Greece.
Boron. Boron is necessary for pollen production and for pollen tube growth, and adequate levels in the styles favour pollen germination and fertilisation, and therefore fruit set [31]. The element moves with difficulty inside the plant towards the young buds, which is why timing matters: trials on pome and stone fruit in Washington State showed that autumn application of boron is more effective than spring application in raising boron in the flowers and improving fruit set [23]. The winter borax application described in Greek practice is compatible with that logic, though no published Greek comparison of the two timings exists.

From bud swell to the end of bloom, March

From the start of bud swell until the bud shows fuzz comes the last copper spray and the last treatment against peach leaf curl, indicatively with dodine or ziram, two substances that the Pacific Northwest handbook names for leaf curl alongside copper, Bordeaux mixture, chlorothalonil, lime sulphur and thiram [3]. Both remain approved active substances in the European Union, the approval of dodine expiring on 15 July 2026 and that of ziram on 31 January 2027; ziram is flagged as a candidate for substitution [14]. The authorisation in force on peach, the rate, the maximum number of applications and the pre-harvest interval are checked each time in the register of the Greek Ministry, which is valid in Greece only [16].
The timing is strict because infection takes place through the bud scales, in mid to late winter, just as the buds begin to swell [3], and because, as the California integrated pest management programme notes, “treatment after symptoms appear is not effective” [2].
After budbreak follows, where needed, a treatment against aphids and scale insects in combination with summer oil.
Brown rot at bloom. The California guidelines place the treatment at 20 to 40% bloom and again at 80 to 100% bloom for susceptible cultivars or when rain and other conditions of high susceptibility prevail [4] [6]. Indicative active substances that remain approved in the European Union are cyprodinil, with approval expiring on 31 October 2026, and difenoconazole, expiring on 15 March 2026 [14]. On nectarines, monitoring for thrips is added.

Three active substances that should no longer be listed as an option

An earlier form of this text suggested, indicatively, three substances that are no longer approved in the European Union. According to the pesticide properties database of the University of Hertfordshire, which tracks the status of every active substance under Regulation 1107/2009 [14]:

cyproconazole, “Not approved”, the inclusion has expired. It was cited for brown rot at bloom.
fenoxycarb, “Not approved”, the inclusion has expired. It was cited as a growth regulator against the lepidopteran pests.
spinetoram, “Not approved”. The European Union approval expired on 30 June 2024, together with those of flubendiamide and spirotetramat [15].

References to these substances have been removed from the text. Substances that remain approved and are mentioned below are chlorantraniliprole, with approval expiring on 31 May 2027, and emamectin benzoate, expiring on 15 November 2026 [14]. Approval at European Union level does not mean authorisation on peach in Greece: that is checked only in the register of the Greek Ministry of Rural Development and Food, whose authorisations are valid in Greece only [16].

Petal fall to fruit growth, April

In this period the fruit grows rapidly and the foliage develops at the same time. The period is critical for supplying the fruit with calcium, for the reason explained in the box that follows. The choice between soil and foliar application, and the amount, are determined by the soil analysis and the leaf analysis of the particular holding; the per-tree amounts that circulated in an earlier form of the text have been removed, because they do not correspond to any published trial.
On alkaline soils the form of nitrogen matters and is not a question of preference. In an experiment with peach trees on calcareous and alkaline soils, rhizosphere pH fell by 2 to 3 units relative to bulk soil pH in all treatments, but the decrease was “slightly less pronounced when plants were supplied with calcium nitrate than with ammonium sulphate”, and the trees given calcium nitrate showed interveinal chlorosis on the apical leaves [24]. On calcareous soils an ammonium form is therefore preferred, such as ammonium sulphate nitrate.
Monitoring traps. Placement is not tied to a date but to the start of the flight, and the date differs by insect. In the San Joaquin Valley of California, pheromone traps for the peach twig borer (Anarsia lineatella) are placed by 20 March [11], for the oriental fruit moth (Grapholita molesta) by 7 February [12] and for San Jose scale around 25 February [10]. For Greece no published biofix date was found; the principle that transfers is that traps go up before the first flight and not after catches have begun, so that the zero point of the degree-day accumulation is set correctly. In mating disruption programmes the dispensers are placed in the upper third of the canopy [12]; it is noted that for the peach twig borer the same source states that “mating disruption has not given reliable control when used alone” [11].

Calcium in peach, how it is actually used

Calcium has low mobility in the phloem. As a review of fruit calcium puts it, “as Ca²⁺ has low phloem mobility, its accumulation in aerial sink organs such as fruit depends on xylem delivery”, that is, on the transpiration stream. The same review notes that “it is during these early stages of fruit development that most Ca²⁺ is delivered” [28]. In practice, the calcium that ends up in the fruit enters early and comes from the root, which is why soil availability and steady irrigation count for more than the number of foliar applications.

Foliar applications work as a supplement, with local action on the fruit surface. In a Greek field trial on cultivar Andross, preharvest sprays of calcium chloride and chelated calcium at 0.12% Ca raised skin calcium by 25 to 42% and flesh calcium by 11 to 17%, with calcium chloride outperforming the chelated form. As regards brown rot, the result needs to be stated precisely: “calcium sprays led to a significant reduction in brown rot development, although no effect on disease incidence was recorded” [29].

More recent work in China, on cultivar Xiahui 8, with a preharvest application of calcium chloride at 50 mM, reported a reduction both in lesion diameter and in the incidence of brown rot after harvest [30]. The reasonable formulation for Greek conditions is therefore that calcium limits the progress of the attack, it does not prevent it, and it does not replace the fungicide programme.

First lepidopteran generations, May

The treatment is not tied to a date but to degree-days from the first catch. For the peach twig borer, the California guidelines state that “best control is obtained when treatments are applied at about 400 degree-days after the start of the flight if the fruit is still green; if the fruit has begun to colour, the treatment is made at 300 degree-days”, while for Bacillus thuringiensis products two applications are foreseen, at 300 to 350 and at 450 to 500 degree-days [11]. For the oriental fruit moth, with long-residual products such as chlorantraniliprole or methoxyfenozide the treatment is placed at 400 degree-days from the first catch, otherwise at 500 to 600 [12].
The active substances that remain approved in the European Union and together cover the lepidopteran pests are chlorantraniliprole and emamectin benzoate [14]; authorisation on peach in Greece, the rate and the pre-harvest interval are checked in the register of the Greek Ministry, valid in Greece only [16]. The interval to a repeat spray is not set by a fixed number of days; it is set by the new catch and by the degree-day accumulation [11] [12].
For the cultivars that ripen in this period, the preharvest treatments against brown rot of the fruit are placed, according to the California guidelines, in the last four weeks before harvest, as needed, since “wetness, from rain or dew, and wounding or cracking of the fruit increase preharvest infection” [5]. In the treatment-timing chart the two preharvest positions are 3 weeks and 1 week before harvest [6]. The interval of 15 to 20 days applied in practice in Central Macedonia falls inside that window, but no published Greek measurement defines it.
On nectarines, from shuck split until the fruit has reached an appreciable size, continuous monitoring is required for the weevil that Greek practice calls “kleonos”, on the basis of observation in the orchards of the district.

Second generation and ripening, June

For the cultivars that ripen during June the same four-week preharvest window for brown rot applies [5], combined with treatments against stink bug and the lepidopteran pests.
The second generation is not expected on a fixed date. For the oriental fruit moth, which in California usually has five generations a year, with a sixth in years with a warm spring and autumn, “the second flight begins about 920 to 1,010 degree-days from the start of the first flight, while in some areas it may appear as early as 800” [12]. The number of generations in Greece depends on the district and does not transfer unchanged from California; what transfers is the method of calculation.

Irrigation in June

Irrigation during fruit growth and through the summer is not interrupted. One of the less obvious reasons concerns the wood-boring insects: according to the California guidelines for peach, “healthy trees exude gum, which usually kills the insects”, whereas “if the tree has injured or weakened areas, this gum accumulation does not develop and the invasion succeeds”. For the shothole borer Scolytus rugulosus the same source states that no insecticide treatment is recommended, and that the key is keeping trees healthy, avoiding sunburn and removing or burning infested wood before the growing season begins [13].

A correction to the wording. The categorical statement that any irrigation deficit causes death of the following year's flower buds does not hold in such absolute terms. A multi-year trial on early peach showed that “deficit irrigation saving up to 40% of water did not lead to significant yield losses over 8 to 9 years”, with canopy development unaffected and only a slight increase in double fruit [32]. The correct formulation is that a controlled deficit at a suitable phase is manageable, while cutting off irrigation is not the same thing as a controlled deficit.

Overlapping generations and ripening, July and August

Trap monitoring continues, and treatments are placed by degree-days, not at a fixed interval [11] [12].
For brown rot, the documented window is the last four weeks before harvest, with treatments placed according to wetness [5]. The 12-day interval applied in practice on susceptible cultivars such as Scarlet, Andross, Venus, Red Gold and Morsiani 60 is field experience on the plain of Central Macedonia and does not correspond to any published Greek measurement.
At the end of August the preparation of the following year begins. The autumn foliar sprays are documented, with one important limitation for zinc: Washington State University reports that “zinc has low retranslocation and a high binding capacity in the plant”, and that autumn application “only improved bud and flower levels and did not affect overall leaf levels, which suggests a need for frequent applications” [23].

Harvest of late cultivars and postharvest nutrition, September

Harvest of the late cultivars, with brown rot treatments continuing inside the preharvest window [5] [6] and with strict observance of the pre-harvest intervals set by the authorisation of each product [16].
Irrigation continues after harvest as well, because the tree goes on photosynthesising and filling its reserves. The importance of those reserves has been measured under a Mediterranean climate: in peach trees of early and late genotypes, “shoot and fruit growth relied mainly on nitrogen remobilised from reserves, which accounted for 72 to 80% of the total nitrogen of the new growth” [27]. The intensity of postharvest irrigation, however, tolerates a controlled deficit without loss of yield [32].
Start of postharvest nutrition with nitrogen and micronutrients, as set out in the corresponding chapter below.
Monitoring for the lepidopteran pests and scale insects continues. For San Jose scale in California, the crawlers from the overwintered females begin to emerge in April with a peak in early May, and the treatment is placed 600 to 700 degree-days after the first catch of males [10].

Leaf fall and dormancy, October, November, December

The application of copper compounds at leaf fall is the single most important measure of the year against peach leaf curl. The Pacific Northwest plant disease management handbook of the United States foresees two applications for western Oregon, at 50% leaf fall and in late dormancy, while east of the Cascade range, where the climate is drier, one application in late dormancy is enough [3]. The choice between the two schemes is decided by how wet the winter of the district is, and that is the criterion which transfers to Greek conditions, not the number of sprays.
Products named for peach leaf curl in the same source: copper compounds, Bordeaux mixture, chlorothalonil, dodine, lime sulphur, thiram and ziram [3]. The authorisation in force in Greece is checked in the register, valid in Greece only [16].
The same timing also serves shot hole, where the treatment is placed at leaf fall before the winter rains, since “the disease is favoured by prolonged wetness from autumn to midwinter” [7].
On holdings with a history of Phytophthora attacks, painting the trunk with ready-made Bordeaux mixture is established practice in the district. The measures that are documented remain drainage, planting berms and more frequent but shorter irrigations [9].

Caution with home-made preparations The practice of drenching the root zone with a home-made solution of copper sulphate and ammonium bicarbonate, a traditional Cheshunt-type recipe, is widespread. That preparation is not among the authorised plant protection products in the register of the Greek Ministry of Rural Development and Food, and only there is it settled what may be used, on which crop and at what rate, and those authorisations are valid in Greece only [16]. For protection against Phytophthora, authorised products are used together with the cultural measures that are documented: correct planting depth, berms, drainage and emitters kept away from the trunk [9].

Sources: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 22 23 24 27 28 29 30 31 32

3. Peach leaf curl, the disease with a single window

Peach leaf curl (Taphrina deformans) is the most dangerous disease of peach. It is worth explaining why the timing is so strict, because this is where most mistakes are made.

When exactly it infects, and why afterwards it is too late

Where it overwinters. “Spores of the fungus overwinter on bark, on twigs and on old infected leaves” [3]. The California integrated pest management programme puts it as follows: “the fungus survives the hot, dry summer as ascospores and bud conidia on the tree surfaces” [2]. It is not, that is, inside the tissue during dormancy, and that is precisely what makes control with a single contact spray at the right moment possible.

When it infects. “Infection occurs through the bud scales in mid to late winter, just as the buds begin to swell” [3]. The conditions have been measured: wetness from rain, dew or irrigation for more than 12.5 hours at a temperature below 16 °C (61 °F in the source) is required, while maximum infection occurs when the trees stay wet for 2 days or more. The optimum temperature for growth of the fungus in laboratory culture is 20 °C (68 °F), with a minimum of 9 °C (48 °F) and a maximum between 26 and 31 °C (79 to 87 °F) [2]. These values come from California and are given as an order of magnitude for the Greek winter, not as a threshold calibrated for Greece.

Why nothing can be done afterwards. Once the fungus has entered the bud it is protected inside the tissue. The same source is categorical: “treatment after symptoms appear is not effective”, and fungicides are applied only during dormancy, after the leaves have fallen and before the new growth emerges [2]. The deformed leaves of April were infected in February. One correctly placed spray is worth more than three late ones.

Sources: 2 3

4. Fertilisation of peach

Peach demands particular knowledge of nutrition. It needs deep, fertile soils with good drainage.

pH, what the foreign guides say and what applies on Greek soils

The formulation “adjust the pH to 6.5 before planting” is often repeated and comes from foreign guides. The University of Georgia sets “a target pH of about 6 to 6.5” and adds that “liming after planting is never as effective as preplant incorporation” [21]. Washington State University gives an optimum range for fruit trees of 6.0 to 7.5 [22].

Transferring that recommendation to Greece is not a neutral act. In Georgia the intervention is upward: the soils are acid and lime is added to raise the pH to 6 or 6.5 [21]. On a calcareous soil the intervention would have to be downward, and that is effectively impossible in a perennial planting: the buffering capacity of the calcium carbonate neutralises any acidification. Published peach orchards on calcareous soils give the order of magnitude: a peach orchard on a calcareous soil with pH 7.8, total calcium carbonate 30%, active lime 10% and only 7 mg/kg of DTPA-extractable iron [25], and an alkaline peach orchard at pH 8.47 in which the rootstock GF677 is used precisely for its tolerance of chlorosis [34].

No published Greek measurement of the pH of peach orchard soils was found while this text was being written, and for that reason no figure is quoted for Greece. What can be said safely is that the recommendation to “adjust the pH to 6.5” is not a measure without cost and must not be copied unquestioned onto a soil that is already calcareous.

What is done instead. First, choice of a rootstock tolerant of chlorosis [34]. Second, an ammonium form of nitrogen, which acidifies the rhizosphere more than the nitrate form and improves micronutrient availability in peach on calcareous soils [24]. Third, realistic expectations of foliar correction: in a field experiment with peach trees on a calcareous soil, “the effects of foliar fertilisation with iron sulfate in deficient leaves were small outside the sprayed leaf area”, that is, iron does not move appreciably even within the leaf itself, and regreening is confined to the part that was wetted [25].

Nutrient removals

The first question is what leaves the field with the harvested crop. The following table circulates widely in the Greek farming press:

Element	Per tonne of fruit
Nitrogen (N)	8 kg
Phosphorus pentoxide (P₂O₅)	2 kg
Potassium oxide (K₂O)	8 kg
Magnesium (Mg)	0.5 kg
Calcium (Ca)	3 kg

The table is attributed to the Greek farming press (Agrotypos) and it was not possible to verify it against a primary publication. The verified international figures are given immediately below.

What exactly these figures measure, and a correction

Much smaller figures appear in the literature, because they measure the fruit alone. The California fertilisation guidelines state that “between 2 and 3 pounds of nitrogen are removed with each ton of peaches harvested”, that is 1.0 to 1.5 kg of nitrogen per tonne, and that “on average 4 to 5 pounds of K₂O are removed per ton of fruit harvested”, that is 2.0 to 2.5 kg of K₂O per tonne [19].

The correction. An earlier form of this text attributed the value of 1.2 kg of nitrogen per tonne to measurements in Pennsylvania. The Pennsylvania source says something different: “peaches remove approximately 0.27 pounds of nitrogen per 100 pounds of fruit” [18], which corresponds to 2.7 kg of nitrogen per tonne, that is roughly twice as much. The value near 1.2 comes from California [19], not from Pennsylvania. The divergence between the two states is real and shows exactly why a removal figure does not transfer without the country and the method of measurement.

The 8 kg in the table correspond to the total annual requirement of the tree per tonne of expected crop, that is, they include what goes into the new growth, into the leaves and into the reserves. That reading is confirmed by work which measured whole trees in bearing peach and concluded that “winter pruning and leaf fall were the events in which most nutrients were removed”, with the results given both per tree and per tonne of fresh fruit [26].

The nitrogen to potassium relationship in peach

In peach the requirements for nitrogen and potassium are at least equivalent, with potassium often slightly higher. The University of Georgia guide for the bearing peach orchard recommends “60 pounds of nitrogen per acre per year for trees at 20 by 20 foot spacing” and “50 to 80 pounds of K₂O per year” to maintain potassium [20], that is, in metric units, about 67 kg of nitrogen and 56 to 90 kg of K₂O per hectare.

An important correction to some figures. An earlier form of this text attributed to the American guides recommendations of the order of 150 to 200 kg of nitrogen and 200 to 250 kg of K₂O per hectare. The sources give clearly lower values: California states that “an annual rate of 25 to 75 pounds of nitrogen per acre is usually adequate” [19], that is 28 to 84 kg per hectare, and Pennsylvania that “trees should typically receive 50 to 100 pounds of nitrogen per acre per year” [18], that is 56 to 112 kg per hectare. The real order of magnitude of the documented recommendations is therefore about 30 to 110 kg of nitrogen and 60 to 90 kg of K₂O per hectare, and not two to three times that.

The relationship with colour is documented explicitly. The Georgia guide states: “The balance of nitrogen and potassium strongly influences red colour during fruit development. Desirable skin and flesh colour has been associated with relatively low nitrogen and high potassium levels in peach halves” [20]. The California guidelines add, from the other side, that “fruit colour is poor on potassium-deficient trees and size is reduced” [19]. In peach, over-fertilisation with nitrogen therefore costs twice over: it produces water sprouts and, at the same time, pale fruit.

Caution against generalising. This relationship does not hold for all stone fruits. Sweet cherry is an exception and requires more nitrogen than potassium, the subject is treated in the article on the annual care of sweet cherry (in Greek). It is one of the points where transferring a recipe from one crop to another leads to error.

When and how the fertiliser is applied

Peach is fertilised in two doses: one in winter and one after bloom, up to thinning. That scheme is compatible with the published recommendations: Pennsylvania states that “spring nitrogen fertilisation or split applications of nitrogen in spring and after harvest appear equally good at meeting the tree's needs” [18].
In years of excessive cropping a supplementary application can be made after shuck fall, always accompanied by irrigation or applied through fertigation, depending on the soil type.
Raising the organic matter of the soil remains a continuing objective, because only in that way is sustainability gained in the crop and in the life of the holding.

How quickly the tree comes into bearing Peach comes into bearing very fast compared with the other fruit trees. The establishment guide of the University of Georgia describes it as follows: “at typical planting distances, trees in the second leaf will carry a small crop of peaches, not large enough to justify the cost of proper management”, and that small crop is removed, while “in the third leaf the trees are managed as bearing trees” [21]. For that reason the trees must grow as fast as possible, so that they have filled the available space by then. Every year of delay in development is lost production that is never recovered.

Sources: 18 19 20 21 22 24 25 26 34

5. Table 2. Suggested fertiliser programmes

The table is indicative, and the fertiliser applications change according to the particular requirements of each holding, on the advice of a specialist agronomist.

What is supported by a source and what is field experience The four proposals that follow are this office's practice on the plain of Central Macedonia and do not correspond to a published trial. The check that can be made is the comparison with the documented ranges. Translated into pure nitrogen per hectare, the proposals give: 400 kg of ammonium sulphate nitrate per hectare, at a typical content of 26%, about 104 kg of nitrogen, in the upper part of the published range of 56 to 112 kg [18]; 800 kg of calcium nitrate per hectare, at a typical content of 15.5%, about 124 kg of nitrogen, above every published range [18] [19] [20] and therefore justified only on soils very poor in calcium and with a high expected yield; 900 kg of potassium magnesium sulphate 0-0-30 per hectare every 2 to 3 years, that is 90 to 135 kg of K₂O a year, also above the range of 56 to 90 kg from Georgia [20]. These divergences do not mean that the proposals are wrong for a particular holding; they mean that soil and leaf analysis are needed before they are applied.

A. Cultivars that yield heavily every year

These cultivars produce a large number of fruits, which have to be of high quality. The trees must stay vigorous without running excessively to wood, because that works against the fruit and against its colour [20].

Proposal 1

Base dressing in late winter with a compound fertiliser such as 11-15-15, 12-11-18+TE, 15-5-20+TE, 15-15-15 or 12-12-17. About 1 kg of fertiliser per 30 kg of expected fruit, as a field practice; the conversion to pure nitrogen is checked against the published ranges [18] [19].
After bloom and fruit drop, an addition of calcium nitrate, or of potassium nitrate as well if there is enough calcium in the soil, in two equal doses. Excessive fertilisation may delay maturity of the crop.
Application of humic and fulvic acids to the soil, as a practice for improving the supply of the elements. No published measurement for peach under Greek conditions was found.
After harvest, postharvest nutrition with nitrogen. The timing is documented: the Georgia guide states that “research indicates that peach tree survival is significantly improved when the annual nitrogen fertilisation is split, with part of the nitrogen applied in mid to late August, after harvest but no later than 1 September, and the remainder in late winter” [20].

Proposal 2

Application every 2 to 3 years, in December and January, of phosphorus, potassium and magnesium. For example, 300 kg per hectare of 0-46-0 combined with 900 kg per hectare of potassium magnesium sulphate 0-0-30, on the alkaline soils.
The application of nitrogen is made annually: in the form of ammonium sulphate nitrate on the alkaline soils rich in calcium carbonate, or of calcium nitrate with boron on soils poor in calcium. The choice of the ammonium form on calcareous soils is supported by the rhizosphere acidification measured in peach trees on calcareous and alkaline soils [24].
The nitrogen can be applied in two doses: half before bloom and half after harvest, a scheme compatible with the recommendations of Pennsylvania [18] and of Georgia [20].

Proposal 3, when earliness is the objective

Where extreme earliness is wanted, nitrogen applications late in the winter are not advised.

Nitrogen fertilisation to be made at 60% at the end of harvest.
The phosphorus, the potassium and the remaining 40% of the nitrogen to be applied in mid to late winter.

The logic is reserve storage: in peach trees of early and late genotypes under a Mediterranean climate, the nitrogen remobilised from reserves accounted for 72 to 80% of the total nitrogen of the new growth, while uptake was relatively low in the first month after budbreak [27]. The particular 60 to 40 split is a field practice and does not come from a published trial.

B. Cultivars with poor fruit set or heavy fruit drop

There are cultivars that do not set satisfactorily, especially on lowland holdings, Big Top and Sweet Scarlet, for example, while at the same time running strongly to wood. Here very moderate fertilisation is required, particularly in the first years and until full bearing. Excessive applications, above all of nitrogen, prevent the plants from forming flower buds and intensify the growth of water sprouts; the Georgia guide notes that “excessive vigour during the summer months causes shading of the developing fruiting wood” [20].

Proposal 4

Conservative fertilisation every winter with a compound fertiliser of low nitrogen content, of the 1-2-2 or 1-2-3 type. Over-fertilisation intensifies the problem of failure to crop.
During flowering, sprays of amino acids or of products with a high content of phosphorus and boron, together with the placing of beehives. The role of boron here is documented: “adequate or high boron levels in the styles can promote pollen germination and pollen tube growth, which benefits pollination, fertilisation and ultimately fruit set and yield” [31].
If excessive fruit set follows pollination, fertilisation with topdressed fertilisers and foliar products follows immediately, so that satisfactory quality is achieved.

For soils with a high pH

On soils with a high pH and established micronutrient deficiencies, iron, boron and zinc are applied as required. Two points need clarifying.

Zinc. On high pH soils, soil zinc “correlates poorly with tree status”, and regular maintenance sprays are recommended [22]. Autumn application improves the levels in the buds and the flowers without affecting the foliage as a whole, so repeated applications are needed [23].

Iron. Foliar correction with iron sulfate acts only on the sprayed area, even within the same leaf, as a field experiment on peach trees on a calcareous soil showed [25]. The chelated forms that remain stable at high pH, such as Fe-EDDHA, are widely used in practice for exactly that reason; no published comparison of the iron forms in Greek peach orchards was found, and the measure with the firmest documentation remains the choice of a rootstock tolerant of chlorosis [34].

Sources: 18 19 20 22 23 24 25 27 31 34

6. After harvest

What has to be done

Fertilisation with nitrogen and micronutrients, mainly boron and zinc, so that the reserves for the next season are secured. The importance of those reserves has been measured: under Mediterranean conditions, remobilised nitrogen covered 72 to 80% of the nitrogen of the new growth of peach [27].

For the autumn foliar sprays there are measured data, although on apple: “remobilised nitrogen contributed 50% of the nitrogen of the shoots in the following season, 90% of the nitrogen of the spur leaves and 60% of the nitrogen of the fruit” [23]. The same source gives the timing: “autumn nitrogen sprays are made after harvest, between October and November, but before natural leaf fall, when the leaves begin to yellow, so that uptake and remobilisation are secured”, with an efficiency ranging from 30 to 80% depending on the weather [23]. The months refer to Washington State; the criterion that transfers is the phenological one, that is before yellowing begins.

For boron, autumn application is more effective than spring application in raising the levels in the flowers and improving fruit set [23] [31]. For zinc, the limitation of low retranslocation described above applies [23].

And the mistake that has to be avoided

Adding a compound fertiliser immediately after harvest is a waste. The reason is chemical and concerns the behaviour of the two elements in the soil:

Phosphorus is “relatively immobile in soil”, diffusing towards the root “only about 0.3 centimetres a year” (one eighth of an inch in the source) [33]. On calcareous soils, where a large part of the Greek peach orchards lies, fixation is added as well: “at very high pH, phosphorus may react with excess calcium to form unavailable compounds”, while the range of maximum availability is pH 6.0 to 7.0 [33].
Potassium is fixed on the colloids of the heavier soils or leached on the sandy ones. This is established soil science, but no measurement for peach orchards under Greek conditions was found, and for that reason no quantification is given.

The result is that fertiliser is paid for and not used, while at the same time the tree is not given what it actually needs at that moment, namely nitrogen and micronutrients [20] [23]. Phosphorus and potassium have their place in the programme, but in late winter and incorporated, not broadcast in September.

Sources: 20 23 27 31 33

7. Sources

The numbers in the text refer to the list below. Where only the abstract was used and not the full text, that is stated explicitly.

[1] Peach Leaf Curl, Peach, Agriculture: Pest Management Guidelines. UC Statewide IPM Program, University of California. Full text of the page. The main source for the timing of the dormant sprays against peach leaf curl in California: application in late November to early December once most of the leaves have fallen, and an additional treatment in January or early February when December and January rainfall is high, and also for the survival of the fungus on the tree surfaces and in the buds.
[2] Prevention and management of peach leaf curl, UC IPM Pest Note 7426, University of California. Full text of the page. Source for the quantitative infection conditions: wetness of more than 12.5 hours at a temperature below 61 °F (16 °C), maximum infection when the trees stay wet for 2 days or more, optimum growth temperature 68 °F (20 °C) with a minimum of 48 °F (9 °C) and a maximum of 79 to 87 °F (26 to 31 °C), for survival as ascospores and bud conidia on the tree surfaces, and for the categorical finding that treatment after symptoms appear is not effective.
[3] Peach (Prunus persica), Leaf Curl. Pacific Northwest Plant Disease Management Handbook. Full text of the page. Source for the overwintering of the spores on bark, twigs and old infected leaves, for infection through the bud scales in mid to late winter as the buds begin to swell, for the scheme of two applications in western Oregon, at 50% leaf fall and in late dormancy, as against one application east of the Cascades, and for the list of active substances: copper compounds, Bordeaux mixture, chlorothalonil, dodine, lime sulphur, thiram and ziram.
[4] Brown Rot Blossom and Twig Blight, Peach. UC Statewide IPM Program. Full text of the page. Source for the timing of the bloom treatments in California: at 20 to 40% bloom and again at 80 to 100% on susceptible cultivars or when rain and conditions of high susceptibility prevail.
[5] Ripe Fruit Rot, Peach. UC Statewide IPM Program. Full text of the page. Source for the preharvest window of the last four weeks before harvest with applications as needed, and for the finding that wetness from rain or dew and wounding or cracking of the fruit increase preharvest infection.
[6] Treatment Timing for Key Diseases, Peach. UC Statewide IPM Program. Full text of the page. Source for the fact that the programme is built by phenological stage and not by month: dormancy, 20 to 40% bloom, 80 to 100% bloom, 3 to 6 weeks after bloom, 3 weeks and 1 week before harvest, with peach leaf curl, shot hole, brown rot, powdery mildew and rust set out in the same table.
[7] Shot Hole Disease, Peach. UC Statewide IPM Program. Full text of the page. Source for the timing of copper at leaf fall or from 15 November to 1 December before the winter rains, for the favourable effect of prolonged wetness from autumn to midwinter, and for the finding that summer rain or sprinkler irrigation favours fruit infection, more heavily low in the tree.
[8] Bacterial Canker, Peach. UC Statewide IPM Program. Full text of the page. Source for the explicit finding that dormant copper application is not effective against bacterial canker, for the strong correlation of disease severity with the presence of the ring nematode in the soil, for the greater susceptibility of trees 2 to 8 years old, and for the strategy of tolerance through rootstock, irrigation and nutrition rather than eradication of the pathogen.
[9] Phytophthora Root and Crown Rot, Peach. UC Statewide IPM Program. Full text of the page. Source for the threshold of 24 hours or more of saturated soil that favours infection, for the reduction of risk through good drainage and more frequent but shorter irrigations, for planting on berms, and for the fact that no rootstock is resistant to every pathogenic species of the genus.
[10] San Jose Scale, Peach. UC Statewide IPM Program. Full text of the page. Source for the dormant treatment with summer oil at low to moderate populations, for placing pheromone traps around 25 February in California, for the emergence of the crawlers in April with a peak in early May, and for the threshold of 600 to 700 degree-days after the first catch of males.
[11] Peach Twig Borer, Peach. UC Statewide IPM Program. Full text of the page. Source for placing traps by 20 March in the San Joaquin Valley and by 1 April in the Sacramento Valley, for the thresholds of 400 degree-days with green fruit and 300 degree-days with colouring fruit, for the two Bacillus thuringiensis applications at 300 to 350 and 450 to 500 degree-days, for the development of the first generation on the shoots in May and June, and for the finding that mating disruption has not given reliable control when used alone.
[12] Oriental Fruit Moth, Peach. UC Statewide IPM Program. Full text of the page. Source for the five generations a year in California with a sixth in years with a warm spring and autumn, for placing traps by 7 February, for the start of the second flight at 920 to 1,010 degree-days and occasionally as early as 800, for the treatment at 400 degree-days with long-residual products such as chlorantraniliprole and methoxyfenozide as against 500 to 600 degree-days otherwise, and for placing the mating disruption dispensers in the upper third of the canopy.
[13] Shothole Borer, Peach. UC Statewide IPM Program. Full text of the page. Source for the fact that healthy trees exude gum which usually kills the insects while injured or weakened areas allow a successful invasion, for the recommendation to keep trees healthy and avoid sunburn as the key to prevention, for burning or removing infested wood before the growing season begins, and for the explicit finding that no insecticide treatment is recommended.
[14] Pesticide Properties DataBase (PPDB), Agriculture & Environment Research Unit, University of Hertfordshire. The individual records for dodine, ziram, cyprodinil, difenoconazole, cyproconazole, fenoxycarb, chlorantraniliprole, spinetoram and emamectin benzoate were opened. Source for the status of each active substance under Regulation 1107/2009: approved, with approval expiry dodine 15/07/2026, ziram 31/01/2027 and a candidate for substitution, cyprodinil 31/10/2026, difenoconazole 15/03/2026, chlorantraniliprole 31/05/2027, emamectin benzoate 15/11/2026; and not approved, with expired inclusion, cyproconazole, fenoxycarb and spinetoram.
[15] EU approval expires for three key PPPs, flubendiamide, spinetoram and spirotetramat. COLEAD. Full text of the bulletin. Source for the specific expiry date of the European Union approval of spinetoram, 30 June 2024, together with those of flubendiamide and spirotetramat.
[16] Βάση εγκεκριμένων φυτοπροστατευτικών προϊόντων [Database of authorised plant protection products], from the register of the Greek Ministry of Rural Development and Food (in Greek). The only valid source for what is permitted today on peach in Greece, at what rate, with what maximum number of applications and with what pre-harvest interval. These are Greek national authorisations and are valid in Greece only; they do not apply in any other country, where that country's own register applies instead. Approval of an active substance at European Union level does not imply an authorised use on peach in Greece.
[17] Potyvirus plumpoxi (PPV000), Datasheet. EPPO Global Database. Full text of the datasheet. Source for the finding that the development of resistant peach varieties remains a challenge because sources of resistance are scarce, in contrast to apricot where cultivars resistant to PPV-D are grown extensively in Spain, for basing control on certified material under the EPPO certification scheme and on the removal of infected trees, for the only limited efficacy of aphicides and summer oils because transmission is non-persistent, and for the presence of the virus in mainland Greece.
[18] Nitrogen Fertilization of Peach Trees, Penn State Extension, Pennsylvania State University. Full text of the page. Source for nitrogen removal with the fruit in Pennsylvania, 0.27 pounds of N per 100 pounds of fruit, that is 2.7 kg per tonne, for the annual recommendation of 50 to 100 pounds of N per acre, that is 56 to 112 kg per hectare, and for the finding that spring fertilisation and split applications in spring and after harvest are equally good.
[19] California Fertilization Guidelines, Peach and Nectarine, CDFA / FREP, California Department of Food and Agriculture. Full text of the page. Source for the removal of 2 to 3 pounds of N per ton of peaches harvested, that is 1.0 to 1.5 kg per tonne, for the 4 to 5 pounds of K₂O per ton, that is 2.0 to 2.5 kg per tonne, for the annual recommendation of 25 to 75 pounds of N per acre, that is 28 to 84 kg per hectare, for the table of requirements by yield level from 63 to 155 pounds of N per acre, and for the finding that on potassium-deficient trees fruit colour is poor and size is reduced.
[20] Cultural Management of the Bearing Peach Orchard (Circular 879), University of Georgia Extension. Full text of the publication. Source for the recommendation of 60 pounds of N per acre per year at 20 by 20 foot spacing, that is about 67 kg per hectare, for the 50 to 80 pounds of K₂O per year, that is 56 to 90 kg per hectare, for the explicit statement that the balance of nitrogen and potassium strongly influences red colour and that desirable skin and flesh colour is associated with low nitrogen and high potassium, for the observation that excessive vigour in summer shades the fruiting wood, and for splitting the nitrogen fertilisation with part of it in mid to late August and no later than 1 September.
[21] Peach Orchard Establishment and Young Tree Care (Circular 877), University of Georgia Extension. Full text of the publication. Source for the target pH of about 6 to 6.5 and for the finding that liming after planting is never as effective as preplant incorporation, a recommendation that concerns the acid soils of Georgia and therefore an upward adjustment of pH, and also for how quickly the tree comes into bearing: a small crop in the second leaf which is removed, and management as bearing trees from the third leaf.
[22] Tree Fruit Soil Fertility and Plant Nutrition in Cropping Orchards in Central Washington, WSU Tree Fruit, Washington State University. Full text of the page. Source for the optimum soil pH range of 6.0 to 7.5 for fruit trees, for the finding that on high pH soils soil zinc correlates poorly with tree status and that regular maintenance zinc sprays are recommended there, and for the link between iron deficiencies and over-irrigation, high water tables and calcareous soils.
[23] Fall Nutrient Sprays in Tree Fruit, WSU Tree Fruit, Washington State University. Full text of the page. Source for the mobilisation and storage of nitrogen in the roots in autumn, for the contribution percentages of remobilised nitrogen in apple, 50% in the shoots, 90% in the spur leaves and 60% in the fruit, for the timing of the autumn nitrogen sprays after harvest, between October and November but before natural leaf fall when the leaves begin to yellow, for the efficiency of 30 to 80% depending on the weather, for the superiority of autumn over spring boron application in raising the levels in the flowers and in fruit set, and for the low retranslocation of zinc that makes frequent applications necessary.
[24] Tagliavini, M., Masia, A. & Quartieri, M. (1995). Bulk soil pH and rhizosphere pH of peach trees in calcareous and alkaline soils as affected by the form of nitrogen fertilizers. Plant and Soil 176:263–271. The abstract was used. Work on PEACH on calcareous and alkaline soils. Source for the fall of rhizosphere pH by 2 to 3 units relative to the bulk soil in all treatments, for the finding that the decrease was slightly less pronounced with calcium nitrate than with ammonium sulphate, and for the appearance of interveinal chlorosis on the apical leaves of the trees supplied with calcium nitrate, the documentation for preferring an ammonium form of nitrogen on calcareous soils.
[25] El-Jendoubi, H., Vázquez, S., Calatayud, Á. and colleagues (2014). The effects of foliar fertilization with iron sulfate in chlorotic leaves are limited to the treated area. A study with peach trees (Prunus persica L. Batsch) grown in the field and sugar beet (Beta vulgaris L.) grown in hydroponics. Frontiers in Plant Science 5:2. Full text, open access, peer reviewed. Field experiment on PEACH. Source for the characteristics of the calcareous orchard soil, pH 7.8, total calcium carbonate 30%, active lime 10% and 7 mg/kg of DTPA-extractable iron, and for the finding that the effects of foliar fertilisation with iron sulfate on chlorotic leaves were small outside the sprayed area, with regreening confined to the part that was wetted.
[26] El-Jendoubi, H., Abadía, J. & Abadía, A. (2013). Assessment of nutrient removal in bearing peach trees (Prunus persica L. Batsch) based on whole tree analysis. Plant and Soil 369:421–437. The abstract was used; the numerical tables were not accessible and for that reason no numerical value from the work is quoted. Source solely for the qualitative finding that winter pruning and leaf fall were the events in which most nutrients were removed, and for the fact that the results are given both per tree and per tonne of fresh fruit.
[27] Policarpo, M., Di Marco, L., Caruso, T., Gioacchini, P. & Tagliavini, M. (2002). Dynamics of nitrogen uptake and partitioning in early and late fruit ripening peach (Prunus persica) tree genotypes under a mediterranean climate. Plant and Soil 239:207–214. The abstract was used. Work on PEACH under a MEDITERRANEAN climate, the closest available to Greek conditions. Source for the finding that shoot and fruit growth relied mainly on nitrogen remobilised from reserves, which accounted for 72 to 80% of the total nitrogen of the new growth, and for the fact that nitrogen uptake was relatively low in the first month after budbreak and faster thereafter.
[28] Hocking, B., Tyerman, S.D., Burton, R.A. & Gilliham, M. (2016). Fruit Calcium: Transport and Physiology. Frontiers in Plant Science 7:569. Full text, open access, peer reviewed. Source for the low mobility of calcium in the phloem and the dependence of its accumulation in the fruit on xylem delivery and the transpiration stream, and for the finding that most of the calcium reaches the fruit in the early stages of its development.
[29] Manganaris, G.A., Vasilakakis, M., Mignani, I., Diamantidis, G. & Tzavella-Klonari, K. (2005). The effect of preharvest calcium sprays on quality attributes, physicochemical aspects of cell wall components and susceptibility to brown rot of peach fruits (Prunus persica L. cv. Andross). Scientia Horticulturae 107(1):43–50. The abstract was used. Trial on a GREEK clingstone cultivar, Andross. Source for the concentration of 0.12% Ca in calcium chloride and in chelated calcium, for the increase in calcium of 25 to 42% in the skin and 11 to 17% in the flesh, for the superiority of calcium chloride over the chelated form, and above all for the precise wording of the result: a significant reduction in the DEVELOPMENT of brown rot with no effect at all on the INCIDENCE of the disease.
[30] Li, S., Guo, S., Xu, J., Cai, Z., Ma, R., Yu, M. & Shen, Z. (2025). Preharvest calcium chloride treatments enhance post-harvest peach fruit resistance to Monilinia fructicola-induced brown rot disease. Postharvest Biology and Technology 222:113368. The abstract was used. Trial in China, cultivar Xiahui 8. Source for the preharvest application of calcium chloride at 50 mM during the exponential fruit growth stage and for the reduction both in lesion diameter and in the incidence of brown rot after harvest.
[31] Fischer, G. and colleagues (2025). The Effect of Boron on Fruit Quality: A Review. Horticulturae 11(8):992. Full text, open access, peer reviewed. A review covering more than one species. Source for the difficulty of moving boron from the source organs to the young buds where it is needed for pollen production and pollen tube growth, and for the finding that adequate or high boron levels in the styles promote pollen germination and pollen tube growth, benefiting pollination, fertilisation and ultimately fruit set.
[32] Wang, D., Zhang, H. & Gartung, J. (2020). Long-term productivity of early season peach trees under different irrigation methods and postharvest deficit irrigation. Agricultural Water Management 230:105940. The abstract was used. Multi-year trial on EARLY PEACH. Source for the finding that deficit irrigation saving up to 40% of water did not lead to significant yield losses over 8 to 9 years, that canopy development remained unaffected and that the incidence of double fruit increased only marginally. It is used to temper the categorical statement that any irrigation deficit destroys the following crop; it does not concern a total cut-off of irrigation.
[33] Managing Phosphorus for Crop Production, Penn State Extension, Pennsylvania State University. Full text of the page. Source for the finding that phosphorus is relatively immobile in soil, diffusing towards the root about one eighth of an inch, that is 0.3 centimetres, a year, for its fixation by iron and aluminium in acid soils and by excess calcium at very high pH, and for the range of maximum availability of pH 6.0 to 7.0.
[34] Song, H.-Y., Zhao, K., Wang, Q., Jiang, G.-L., Sun, S.-X., Li, J., Tu, M.-Y., Wang, L.-L., He, C.-Y., Wang, T. & Chen, D. (2025). Mechanism for efficient nitrogen utilization by peach rootstock GF677 (Prunus amygdalus × Prunus persica) in alkaline orchard soils. Frontiers in Plant Science 16:1699942. Full text, open access, peer reviewed. Source for the pH value of 8.47 of the alkaline peach orchard soil of the study, a documented example of peach grown at a pH far above the “optimum” of the foreign guides, and for the use of the rootstock GF677 precisely because of its tolerance of chlorosis.

Disclaimer This text is informative and educational in character and does not constitute a prescription for the application of plant protection products or fertilisers. Active substances are mentioned indicatively; authorisations, rates and pre-harvest intervals change and must be checked each time in the current database of authorised plant protection products of the Greek Ministry of Rural Development and Food. Those authorisations are Greek national authorisations and are valid in Greece only. They do not apply in any other country, where the national register of that country applies instead, and readers outside Greece must check the authorisations, rates, growth stages and pre-harvest intervals in force where they are before any application. The decision on the method and the amount of fertilisation must always be taken in consultation with an agronomist; incorrect fertilisation can produce the opposite of the intended result. Fertilisation is always carried out with the protection of the environment and the sustainability of the holding in view. The author and Pastopoulos Agronomics accept no liability for damage caused by misuse of this manual.