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Strawberry Fertilization Guidelines

Funding provided by:
FREP
 
 
 

Nitrogen
(N)

 

Strawberry Nitrogen Nutrition

Deficiency Symptoms

Slight N deficiency is characterized by light-green older leaves. As deficiency progresses, leaves become uniformly yellow and their size is reduced. As leaves age, leaf stalks and blades may turn reddish. Flowers and fruits of N deficient plants are smaller [N35]. Nitrogen and P deficiency may both result in reddish or purple leaves. However, while other leaves of N deficient plants are pale-green, they tend to be dark green when P is deficient. A diagnosis based on deficiency symptoms is best confirmed with leaf analyses [N4].

Excessive Nitrogen

Heavy N fertilization can lead to excessive leaf growth and poor fruit quality [N35]. Heavy N fertility or frequent irrigation during an overcast period following warm weather may cause fruit albinism [N5]. Susceptibility to pathogens, such as Botrytis fruit rot (Botrytis cinerea; also known as gray mold) and anthracnose (Colletotrichum acutatum) may be increased when N is available in excess [N36].

Phosphorus
(P2O5)

 

Strawberry Phosphorus Nutrition

Deficiency Symptoms

Phosphorus deficient plants grow slowly and are dark green. Leaves are small and the underside of the leaf blade may be purple, while a metallic lustre develops on the upper side. Flowers and fruits of P deficient plants tend to be smaller [P16]. Nitrogen and P deficiency may both result in reddish or purple leaves. However, while other leaves are pale-green under N deficiency, they tend to be dark green when P is deficient. A diagnosis based on deficiency symptoms is best confirmed with leaf analyses [P2].

Potassium
(K2O)

 

Strawberry Potassium Nutrition

Deficiency Symptoms

The first symptom of K deficiency is often a tanning, browning and drying of the upper margin of young, mature leaves. The symptoms progress inwards between the veins. At the same time, the lower blade area, including the midrip and part of the petiole darken and become dry. Predominantly older leaves are affected, while younger leaves remain healthy. Fruits of K deficient plants are light in color, pulpy in texture and taste insipid [K19].

Soil Test

Soil Nitrate Test

The root system of strawberry plants is relatively shallow. Even though roots may extend to a depth of two feet in light sandy soils, most roots are found in the top foot of the profile [N22, N37]. Soil samples are therefore generally taken from the top 6-10 inches of the profile [N29]. For more information on sampling procedure see Sampling for Soil Nitrate Determination.

Soil nitrate N is typically high when strawberries are planted after vegetables. Monitoring soil mineral N during the winter and early spring instead of applying a large amount of preplant N can increase N use efficiency and reduce the risk of nitrate leaching during the winter months [N6].

Leaf Analysis

Leaf Analysis

Leaf Sampling

Systematic plant analysis is a useful tool to monitor the nutritional status of strawberry plants. Leaf analyses are performed on young mature leaves. Approximately 30-40 leaves should be collected for one composite sample. The leaves are taken at equidistant intervals across the rows of a field or sampling block [N35]. Non-uniform fields should be divided into blocks which are sampled separately. Separate samples should also be taken from areas that differ greatly from the rest of the field [N34]. The three leaflets are separated from the petiole and placed into a pre-labeled paper bag. The samples are either kept cool and sent to the lab immediately, or they may be dried in an oven at 160 to 175 °F (70-80 °C). For more information on sampling procedure see Plant Tissue Sampling.

Interpretation of Results

Optimal leaf nutrient concentrations were determined in a study in 53 commercial fields with ‘Albion’ strawberries located in the Watsonville-Salinas and Santa Maria areas over two production seasons (see Table) [N13]. The concentrations reported in the table are from high-yielding fields. Therefore, critical values may be lower.

Optimum leaf N, P and K concentrations [N13].
Optimum
                      leaf P and K concentrations

Petiole nitrate N concentrations are much more variable and less reliable than leaf total N. Maintaining nitrate N levels above 1,000 ppm pre-harvest and above 400 ppm during harvest is likely adequate to ensure high productivity [N13]. This recommendation is in line with an earlier study carried out in San Jose, where the critical petiole nitrate N concentration was 500 ppm. Lower values indicated N deficiency, while very high nitrate-N values (above 10,000 ppm) generally resulted in excessive leaf growth and reduced yield [N35].

Preplant N

Preplant Nitrogen

A moderate amount of preplant controlled release fertilizer in combination with regular monitoring of soil mineral N during the winter minimize the risk of nitrate leaching, while ensuring that suboptimal N availability would be detected [N6]. The rest of the N is fertigated throughout the fruiting season to meet crop N uptake [N7].

Nitrogen Uptake

In the northern production areas, N uptake of fall-planted strawberries is slow during the winter months. In a study carried out in 26 commercial fields in the Salinas and Pajaro Valleys, N uptake averaged less than 25 lbs/acre through March [N6].

N Uptake Curve
Strawberry N Uptake Curve [N6].

In the Ventura area, where strawberries are planted in early fall, early N uptake is higher.
For more information see Strawberry Nitrogen Uptake and Partitioning.

Application Rate

Based on the N uptake curve, strawberry plants generally need little N until spring. Several studies found that the preplant fertilizer rate has a marginal effect on marketable strawberry yield if sufficient fertilizer is supplied by the drip irrigation system as soon as the plant roots are able to absorb it [N2, N6, N25, N26]. However, Bendixen [N3] reported a positive effect of application rates exceeding 80 lbs/acre in some fields.

The application rate needs to be adjusted for residual soil nitrate concentrations, which are typically high when strawberries are planted after vegetables. A moderate preplant N application provides insurance in case of nitrate loss during crown establishment and with winter rain [N12].

The N release rate of controlled release fertilizers needs to be taken into account as well. Common controlled release fertilizers release N at a relatively steady rate over 6-8 months. This means that if applied in late October more than half the N is likely to be released by the end of March. Nitrogen released in excess of crop N uptake is subject to leaching by rain or irrigation water [N14].

Mode of Application

Band application is more effective than broadcasting the fertilizer and incorporating it [N15]. The fertilizer band is generally applied 4-6 inches below the bed surface. The band can be directly below the plant rows or up to 2 inches to the side [N3, N6].

Strawberry plants are very sensitive to salinity and chloride [N8, N20, N32]. Direct root contact with fertilizer needs to be avoided. This is especially important when immediately available N and K fertilizers are used instead of controlled release material.

Fertilizer Type

The preplant application of controlled release fertilizer (CRF) is a nearly universal practice in the California strawberry industry. The fertilizers commonly used are typically rated as 6-8 month nutrient release [N7].

While some studies reported that controlled release fertilizers were more effective than immediately available fertilizers [N18], other studies found little or no difference [N2, N25]. The advantage of controlled release fertilizer over immediately available N material is likely more pronounced when large amounts are applied and when the risk of nitrate leaching during the winter is high.

Controlled release fertilizer release N at a relatively constant rate, while N uptake by plants is much higher in spring and throughout the summer than during the winter months. Therefore crop N uptake cannot be matched well with a program relying entirely on controlled release fertilizer applied preplant [N6].

Several studies reported that N uptake and biomass production was higher when both, ammonium and nitrate were present than with either ammonium or nitrate alone [N10, N27, N30]. Field studies, however, did not find yield differences when plants were fertilized with urea, ammonium or nitrate [N2, N18, N25, N26]. One study reported that fertilization with ammonium sulfate reduced black root rot (Rhizoctonia Fragariae) by 10% compared to calcium nitrate [N9].

Time of Application

Preplant fertilizers are applied before the plastic mulch is spread.

    N Fertigation

Nitrogen Fertigation

Split applications have been found to produce higher yields compared to a program where all the N is applied preplant [N18].

Application Rate

In a study carried out in the Salinas and Pajaro Valleys, N accumulation in the aboveground biomass increased linearly by 1 lb/acre per day from April through mid-September, reaching 186 lbs/acre by mid-September. Including roots, which generally contain less than 10% of the plant’s total N content [N21, N31], the seasonal N uptake reached 200 lbs/acre [N6]. For more information see Strawberry Nitrogen Uptake and Partitioning.

The average yield in these fields was 35.8 tons/acre and the N content of the fruits averaged 0.12% (1.2 g/kg fresh weight). N uptake was nearly evenly divided between vegetative tissue and fruits [N6].

Nitrogen released from controlled release fertilizer applied in fall needs to be taken into account when calculating the application rates for fertigation.

CropManage

Residual soil nitrate and nitrate in the irrigation water can supply significant amounts of N to crops. These N sources are taken into account by CropManage, a web-based irrigation and N management decision support tool developed by UC Cooperative Extension. The program integrates CIMIS reference ET data and field specific soil, plant and management information to calculate crop water needs and estimates fertilizer N needs on a field-by-field basis. CropManage is free to use and can be accessed here and an overview of the program can be found here.

Mode of Application

Fertigation is a very efficient way to apply N [N17]. It is best to irrigate before injecting the dissolved fertilizer to keep it within the root zone [N33]. To ensure even distribution of N throughout the field, the system needs to run until the fertilizer is flushed from the drip tape farthest from the point of injection.

Fertilizer Type

A commonly used fertilizer for fertigation is UAN [N16]. Urea, ammonium sulfate and calcium nitrate can also be used [N33].

Time of Application

The consistent crop N uptake rate over the entire fruiting season suggested that a program of small, uniform N fertigations throughout that period is an efficient practice that minimizes summer nitrate loss potential [N7].

Locascio and coworkers [N19] found no difference in strawberry yield when N and K were applied either daily or weekly with the trickle irrigation.

Foliar N

Foliar Nitrogen

When soil fertility is managed properly, foliar-applied N-P-K fertilizers applied during flowering, fruit enlargement and/or flower initiation generally have minimal effects on strawberry production [N1, N24]. The flexibility of N fertigation with drip irrigation systems reduces the need for foliar N even further. When root uptake is limited, foliar-N applications may be an effective way to supply N [N23].

For Oregon, Hart and colleagues recommend limiting the N applied with foliar urea to 10 lbs N/acre per application [N11]. In a study carried out in Oregon, foliar application of a 5% urea solution (23 g N/L) did not damage leaves [N28]. Plots were treated in the early morning with the equivalent of 75 gallons of water per acre, thus applying 14.4 lbs N/acre [N28]. Nestby and Tagliavini [N23] reported that a larger proportion of the urea was taken up at first fruit ripening than at anthesis.

Soil Test

Soil Analysis

Soil Sampling

The root system of strawberry plants is relatively shallow. Even though roots may extend to a depth of two feet in light sandy soils, most roots are found in the top foot of the profile [P10, P17]. Soil samples are therefore generally taken from the top 6-10 inches of the profile [P14]. Soil samples are generally taken during the summer or fall before planting so that P, lime and other nutrients can be applied before planting. For more information on sampling procedure see Soil Test Sampling.

Phosphorus availability is generally determined by extracting soil samples with a bicarbonate solution (Olsen-P).

Interpretation of Results

No University of California soil test interpretation guidelines specific to strawberries are available. In general, bicarbonate extractable P concentrations above 25 ppm are considered high, while concentrations between 15 and 25 ppm are considered adequate (see Table) [P4].

Generalized soil interpretative guide [P4].
Soil P and
                      K test interpretation

In a two-year study in two fields located south of Salinas with Olsen P values of 90 ppm, Mark Bolda found no difference in yield and petiole or leaf P concentrations between fertilized and unfertilized plots [P3].

Leaf Analysis

Leaf Analysis

Leaf Sampling

Systematic plant analysis is a useful tool to monitor the nutritional status of strawberry plants. Leaf analyses are performed on young mature leaves. Approximately 30-40 leaves should be collected for one composite sample. The leaves are taken at equidistant intervals across the rows of a field or sampling block [P16]. Non-uniform fields should be divided into blocks which are sampled separately. Separate samples should also be taken from areas that differ greatly from the rest of the field [P15]. The three leaflets are separated from the petiole and placed into a pre-labeled paper bag. The samples are either kept cool and sent to the lab immediately, or they may be dried in an oven at 160 to 175 °F (70-80 °C). For more information on sampling procedure see Plant Tissue Sampling.

Interpretation of Results

Optimal leaf nutrient concentrations were determined in a study in 53 commercial fields with ‘Albion’ strawberries located in the Watsonville-Salinas and Santa Maria areas over two production seasons (see Table) [P8].

Optimum leaf N, P and K concentrations [P8].
Optimum
                      leaf P and K concentrations

The same study found that maintaining petiole PO4-P concentrations above 1,200 ppm throughout the season should ensure P sufficiency [P8]. As this level is based on a survey in the Coastal area in fields with high soil P availability, the actual critical value may be lower [P8].

Preplant P

Preplant Phosphorus

Application Rate

The P application rate should be adjusted based on soil test results. With high soil P concentrations (>25 ppm Olsen-P), little or no fertilization is required. If soil P availability is adequate, applying the amount of P removed with the harvested strawberries ensures that soil P availability remains in the optimal range in the long term. The application rate may need to be increased when the soil P test suggests low P availability (<15 ppm). Contact your local farm advisor for more information.

Based on late season whole plant samples from commercial fields in the Santa Maria and Watsonville-Salinas districts, seasonal uptake reached 90 lbs P2O5/acre (40 lbs P/acre) [P7]. About half of the P was removed with harvested fruits, while the other half was in the vegetative tissue. Therefore, an annual application of 45 lbs P2O5/acre is sufficient to replace the P removed from the field with harvested fruits.

Removal of P in fruits was based on a marketable yield of 30 tons/acre, a dry matter content of 9%, P concentration of 0.35% in the dry matter and a cull rate of 15% [P7]. Slightly lower P concentrations of 0.23-0.33% in the dry matter of fruits were reported by Welch and Quick [P18].

Mode of Application

Phosphorus is immobile in the soil, it is therefore used with greater efficiency when incorporated or banded at a depth of 4-6 inches [P5].

Phosphorus fertilizer is best banded on both sides of the row at a distance of 3-4 inches from the plants. Alternatively, P can be broadcast and disked into the top 6 inches of soil [P11, P12].

Fertilizer Type

A number of granular and liquid P fertilizers are available. Fact sheets of the most common fertilizers can be found on the web site of the International Plant Nutrition Institute.

Time of Application

Phosphorus fertilizer can be worked into the soil prior to preparing the bed and spreading the plastic [P12].

In-Season P

In-Season Phosphorus

A large number of studies in many plant species have shown that early season P supply is critical for optimum crop yield [P5]. For this reason, P is generally applied pre-plant.

Phosphorus can be fertigated with drip irrigation systems. However, in irrigation water with appreciable calcium content, insoluble calcium phosphate is formed which may plug the emitters [P4].

Foliar P

Foliar Phosphorus

When soil fertility is managed properly, foliar N-P-K fertilizers applied during flowering, fruit enlargement and/or flower initiation generally have minimal effects on strawberry production [P1, P13].

High salinity can reduce phosphorus and potassium uptake. Kaya and coworkers [P9] showed that foliar application of a 4 mM solution of KH2PO4 can partially mitigate the adverse effects of salinity on plant growth and fruit yield [P9]. Foliar fertilizer was applied twice a week from August to November and preharvest from March to April.

Soil Test

Soil Analysis

Soil Sampling

The root system of strawberry plants is relatively shallow. Even though roots may extend to a depth of two feet in light sandy soils, most roots are found in the top foot of the profile [K13, K20]. Soil samples are therefore generally taken from the top 6-10 inches of the profile [K15]. A soil sample should be analyzed during the summer or fall before planting. Testing during this timeframe allows the grower to apply fertilizer during the fall before planting and to disk it down into the top 6 inches of soil [K14]. For more information on sampling procedure see Soil Test Sampling.

Potassium availability is generally determined by extracting soil samples with an ammonium aceatate solution.

Interpretation of Results

No University of California soil test interpretation guidelines specific to strawberries are available. In general, ammonium acetate extractable K concentrations above 200 ppm are considered high, while concentrations between 150 and 200 ppm are considered adequate (see Table) [K3].

Generalized soil interpretative guide [K3].
Soil P and
                      K test interpretation

For Western Oregon, Hart and coworkers [K5] recommended an intermediate range of 75-175 ppm.

Leaf Analysis

Leaf Analysis

Leaf Sampling

Systematic plant analysis is a useful tool to monitor the nutritional status of strawberry plants. Leaf analyses are performed on young mature leaves. Approximately 30-40 leaves should be collected for one composite sample. The leaves are taken at equidistant intervals across the rows of a field or sampling block [K19]. Non-uniform fields should be divided into blocks which are sampled separately. Separate samples should also be taken from areas that differ greatly from the rest of the field [K18]. The three leaflets are separated from the petiole and placed into a pre-labeled paper bag. The samples are either kept cool and sent to the lab immediately, or they may be dried in an oven at 160 to 175 °F (70-80 °C). For more information on sampling procedure see Plant Tissue Sampling.

Interpretation of Results

Optimal leaf nutrient concentrations were determined in a study in 53 commercial fields with ‘Albion’ strawberries located in the Watsonville-Salinas and Santa Maria areas over two production seasons (see Table) [K7].

Optimum leaf N, P and K concentrations [K7].
Optimum
                      leaf P and K concentrations

The same study found that maintaining petiole K above 2.5% preharvest, and above 1.5% during harvest, appeared to be adequate [K7]. As these concentrations are based on a survey in fields with high K availability, the actual critical values may be lower.

Preplant K

Preplant Potassium

Application Rate

The K application rate should be adjusted based on soil test results. With high soil test K values (>200 ppm), which are not uncommon in coastal strawberry fields, little or no K fertilizer is required. If soil K availability is adequate, applying the amount of K removed with the harvested strawberries ensures that soil K availability remains in the optimal range in the long term. The application rate may need to be increased when the soil K test suggests low availability (<150 ppm).

Based on late season whole plant samples from commercial fields in the Santa Maria and Watsonville-Salinas districts, seasonal uptake reached 290 lbs K2O/acre (240 lbs K/acre) [K6]. Of this, about 170 lbs K2O/acre (140 lbs K/acre) were removed with harvested fruits, while the rest was in the vegetative tissue. Therefore, an annual application of 170 lbs K2O /acre is sufficient to replace the K removed from the field with harvested fruits. The economically optimal K rate may be lower. Contact your local farm advisor for more information.

Removal of K in fruits was based on a marketable yield of 30 tons/acre, a dry matter content of 9%, K concentration of 2.2% in the dry matter and a cull rate of 15%. Slightly lower K concentrations of 1.6-2.0% in the dry matter of fruits were reported by Welch and Quick [K21].

Mode of Application

The strawberry plant is very sensitive to salinity and chloride [K3, K12, K16]. For this reason, direct root contact with fertilizer needs to be avoided [K4]. For Oregon, Hart and coauthors recommended banding no more than 60 lbs K2O/acre with N and P at planting. Higher rates should be broadcast before planting [K5].

Band application is more effective than broadcasting the fertilizer and incorporating it. In sandy soils with a low cation exchange capacity, the risk of K leaching as broadcasting is increased, especially when the material is broadcast [K8].

Fertilizer Type

A study carried out in Florida on a sandy soil found that potassium sulfate and potassium chloride produced the same total fruit yields and leaf-tissue K concentrations [K11].

A grower experiencing a situation of high sodium and chloride, however, should avoid using potassium chloride [K2]. Potassium nitrate or potassium sulfate can be used instead [K17].

Time of Application

Preplant K can be worked into the soil prior to preparing the bed and applying the plastic [K14].

    K Fertigation

Potassium Fertigation

Application Rate

The amount of fertilzer K required during the growing season depends on K uptake by the plants, soil K availability, and the amount of K applied preplant (see Preplant K).

Mode of Application

During the growing season, K is best fertigated. It is best to irrigate before injecting the dissolved fertilizer to keep it within the root zone [K17]. To ensure even distribution of N throughout the field, the system needs to run until the fertilizer is flushed from the drip tape farthest from the point of injection.

Fertilizer Type

The strawberry plant is very sensitive to salinity and chloride [K3, K12, K16].

In a study carried out in Florida, Albregts and coworkers [K1] found that weekly applications of 10 lbs K2O/acre in the form of KCl applied by drip irrigation to strawberries grown on polyethylene-mulched beds had no negative effects. However, on soils with a high sodium and chloride concentrations, KCl should not be used [K2]. Potassium nitrate or potassium sulfate can be used instead [K17].

Time of Application

The fruits accumulate more K than all other plant organs combined [K6, K8]. Therefore, sufficient K needs to be supplied from flowering through harvest.

Foliar K

Foliar Potassium

Foliar KH2PO4 sprays have been found to ameliorate the negative effects of salinity on plant growth and fruit yield. Tissue concentrations of P and K were in the deficient range in plants grown at high NaCl and these deficiencies were corrected by foliar KH2PO4 [K9]. Fertigated potassium sulfate has also been found to ameliorate the negative effects of high NaCl concentrations [K10].

Acknowledgments

Guidelines and Webpage Design:

  • Daniel Geisseler, Ph.D.; Post Doctoral Scientist; Department of Land, Air and Water Resources, University of California, Davis

Reviewers:

  • Timothy K. Hartz, Ph.D.; Extension Specialist/Agronomist; Department of Plant Sciences, University of California, Davis
  • William R. Horwath, Ph.D.; Professor of Soil Biogeochemistry and James G. Boswell Endowed Chair in Soil Science; Department of Land, Air and Water Resources, University of California, Davis

Support:

  • Amadou Ba, Ph.D.; Branch Chief Feed, Fertilizer, and Livestock Drugs Regulatory Services, California Department of Food and Agriculture
  • Amrith Gunasekara, Ph.D.; Science Advisor to the Secretary; California Department of Food and Agriculture

Last Update: September, 2014

Additional Information:

  1. Strawberry Nitrogen Uptake and Partitioning
  2. Strawberry Production in California
    (Historic Background, Production Statistics)
  3. FREP Database

References:


TOP OF PAGE

Nitrogen

  1. Albregts, E.E., Howard, C.M., 1986. Response of strawberries Fragaria-ananassa to soil and foliar fertilizer rates. HortScience 21, 1140-1142.
  2. Albregts, E.E., Clark, C.A., Stanley, C.D., Zazueta, F.S., Smajstrla, A.G., 1991. Preplant fertilization of fruiting microirrigated strawberry. HortScience 26, 1176-1177.
  3. Bendixen, W.E., 1998. Evaluation of controlled release fertilizers and fertigation in strawberries and vegetables. FREP Final Report.
  4. Bolda, M., 2011. What does nitrogen deficiency really look like in strawberry? Strawberries and Caneberries. University of California Agriculture and Natural Resources Blog.
  5. Bolda, M., 2012. Albino strawberry fruit. Strawberries and Caneberries. University of California Agriculture and Natural Resources Blog.
  6. Bottoms, T.G., Hartz, T.K., Cahn, M.D., Farrara, B.F., 2013. Crop and soil nitrogen dynamics in annual strawberry production in California. HortScience 48, 1034–1039.
  7. Cahn, M., 2012. Optimizing irrigation and nitrogen management in strawberries for improved water quality. Final Report to the Central Coast Regional Water Quality Control Board.
  8. California Plant Health Association, 2002. Western Fertilizer Handbook 9th edition. Interstate Publishers, Inc.
  9. Elmer, W.H., La Mondia, J.A., 1995. The influence of mineral nutrition on strawberry black root rot. Advances in Strawberry Research 14, 42-48.
  10. Ganmore-Neumann, R. Kafkafi, U., 1985. The effect of root temperature and nitrate/ammonium ratio on strawberry plants. II. Nitrogen uptake, mineral ions, and carboxylate concentrations. Agronomy Journal 77, 835-840.
  11. Hart, J., Righetti, T., Sheets, A., Martin, L.W., 2000. Strawberries (Western Oregon – West of Cascades). Oregon State University Extension Service Fertilizer Guide FG 14.
  12. Hartz, T.K., 2011. Strawberry nutrient management.
  13. Hartz, T.K., 2012. Establishing nutrient management practices for high-yield strawberry production. California Strawberry Commission Annual Production Research Report 2011-2012.
  14. Hartz, T.K. and Bolda, M., 2011. Fertilizer management in strawberry production. Strawberries and Caneberries. University of California Agriculture and Natural Resources Blog.
  15. Hochmuth, G. and Cordasco, K., 2009. A summary of N and K research with strawberry in Florida. University of Florida Extension Publication HS752.
  16. Hochmuth, G.J., Albregts, E.E., Chandler, C.C., Cornell, J., Harrison, J., 1996. Nitrogen fertigation requirements of drip-irrigated strawberries. Journal of the American Society of Horticultural Sciences 121, 660–665.
  17. Latet, G., Meesters, P., Bries, J., 2002. The influence of different nitrogen (N) strategies on the yield and leaching in open field strawberry production. Acta Horticulturae 567, 455-458.
  18. Locascio, S.J., Martin, F.G., 1985. Nitrogen source and application timing for trickle irrigated strawberries. Journal of the American Society of Horticultural Sciences 110, 820-823.
  19. Locascio, S.J., Myers, J.M., Martin, F.G., 1977. Frequency and rate of fertilization with trickle irrigation for strawberries. Journal of the American Society of Horticultural Science 102, 456-458.

  20. TOP OF PAGE

  21. Martinez Barroso, M.C., Alvarez, C.E., 1997. Toxicity symptoms and tolerance of strawberry to salinity in the irrigation water. Scientia Horticulturae 71, 177-188.
  22. May, G.M., Pritts, M.P., Kelly, M.J., 1994. Seasonal patterns of growth and tissue nutrient content in strawberries. Journal of Plant Nutrition 17, 1149-1162.
  23. Nelson, P.E., Wilhelm, S., 1957. Some anatomic aspects of the strawberry root. Hilgardia 26, 631-642.
  24. Nestby, R., Tagliavini, M., 2005. Foliar uptake and partitioning of urea-N by strawberry plants as affected by timing of supply and plant N status. Journal of Horticultural Science & Biotechnology 80, 272–275.
  25. Rosen, C.J., Hoover, E.E., Luby, J.J., 1988. Influence of foliar-applied N-P-K fertilizers on productivity and nutrition of June-bearing strawberries. Canadian Journal of Plant Science 68, 277-282.
  26. Santos, B.M., 2010. Effects of preplant nitrogen and sulfur fertilizer sources on strawberry. HortTechnology 20, 193-196.
  27. Santos, B.M., Whidden, A.J., 2010. Nitrogen fertilization of strawberry cultivars: Is preplant starter fertilizer needed? University of Florida Extension publication HS 1116.
  28. Sas, L., Marschner, H., Roemheld, V., Mercik, S., 2003. Effect of nitrogen forms on growth and chemical changes in the rhizosphere of strawberry plants. Acta Physiologiae Plantarum 25, 241-247.
  29. Strik, B., Righetti, T., Buller, G., 2004. Influence of rate, timing, and method of nitrogen fertilizer application on uptake and use of fertilizer nitrogen, growth, and yield of June-bearing strawberry. Journal of the American Society of Horticultural Sciences 129, 165-174.
  30. Strik, B.C., 2013. Nutrient management of berry crops in Oregon.
  31. Tabatabaei, S.J., Yusefi, M., Hajiloo, J., 2008. Effects of shading and NO3:NH4 ratio on the yield, quality and N metabolism in strawberry. Scientia Horticulturae 116, 264–272.
  32. Tagliavini, M., Baldi, E., Lucchi, P., Antonelli, M., Sorrenti, G., Baruzzi, G., Faedi, W., 2005. Dynamics of nutrients uptake by strawberry plants (Fragaria x Ananassa Dutch.) grown in soil and soilless culture. European Journal of Agronomy 23, 15–25.
  33. Tanji, K.K., Kielen, N.C., 2002. Agricultural drainage water management in arid and semi-arid areas. FAO Irrigation and Drainage Paper 61. FAO, Rome.
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  35. Ulrich, A., 1976. Plant tissue analysis as a guide in fertilizing crops. In: Reisenauer, H.M. (Ed.). Soil and Plant-Tissue Testing in California. University of California Cooperative Extension Bulletin 1879. pp. 6-8.
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TOP OF PAGE

Phosphorus

  1. Albregts, E.E., Howard, C.M., 1986. Response of strawberries Fragaria-ananassa to soil and foliar fertilizer rates. HortScience 21, 1140-1142.
  2. Bolda, M., 2011. What does nitrogen deficiency really look like in strawberry? Strawberries and Caneberries. University of California Agriculture and Natural Resources Blog.
  3. Bolda, M., 2012. Testing the effectiveness in strawberry of phosphorus fertilizer additions in high phosphorus concentration soils. Strawberries and Caneberries. University of California Agriculture and Natural Resources Blog.
  4. California Plant Health Association, 2002. Western Fertilizer Handbook 9th edition. Interstate Publishers, Inc.
  5. Grant, C.A., Flaten, D.N., Tomasiewicz, D.J., Sheppard, S.C. 2001. The importance of early season phosphorus nutrition. Canadian Journal of Plant Science 81, 211–224.
  6. Hart, J., Righetti, T., Sheets, A., Martin, L.W., 2000. Strawberries (Western Oregon – West of Cascades). Oregon State University Extension Service Fertilizer Guide FG 14.
  7. Hartz, T.K., 2011. Establishing nutrient diagnostic standards for high-yield strawberry production. California Strawberry Commission Annual Production Research Report 2010-2011. pp. 41-50.
  8. Hartz, T.K., 2012. Establishing nutrient management practices for high-yield strawberry production. California Strawberry Commission Annual Production Research Report 2011-2012.
  9. Kaya, C., Kirnak, H., Higgs D., 2001. An experiment to investigate the ameliorative effects of foliar potassium phosphate sprays on salt-stressed strawberry plants. Australian Journal of Agricultural Research 52, 995–1000.
  10. Nelson, P.E., Wilhelm, S., 1957. Some anatomic aspects of the strawberry root. Hilgardia 26, 631-642.
  11. Ontario Ministry of Agriculture and Food, 2012. Guide to fruit production 2014-15.
  12. Penn State Cooperative Extension, 2013. The Mid-Atlantic Berry Guide, 2013–14. Chapter 6: Strawberries. pp. 49-114.
  13. Rosen, C.J., Hoover, E.E., Luby, J.J., 1988. Influence of foliar-applied N-P-K fertilizers on productivity and nutrition of June-bearing strawberries. Canadian Journal of Plant Science 68, 277-282.
  14. Strik, B.C., 2013. Nutrient management of berry crops in Oregon.
  15. Ulrich, A., 1976. Plant tissue analysis as a guide in fertilizing crops. In: Reisenauer, H.M. (Ed.). Soil and Plant-Tissue Testing in California. University of California Cooperative Extension Bulletin 1879. pp. 6-8.
  16. Ulrich, A., Mostafa, M.A.E., Allen, W.W., 1992. Strawberry deficiency symptoms: A visual and plant analysis guide to fertilization. University of California, Division of Agriculture and Natural Resources. Bulletin 1917.
  17. Weaver, J.E., Bruner, W.E., 1927. Root development of vegetable crops. McGraw-Hill Book Company, Inc., NY. 351 pp.
  18. Welch, N.C., Quick, J., 1981. Fertilizing summer-planted strawberries in California’s Central Coast. California Agriculture 35(9), 26-27.
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Potassium

  1. Albregts, E.E., Hochnmth, G.J., Chandler, C.K., Cornell, J., Harrison, J., 1996. Potassium fertigation requirements of drip-irrigated strawberry. Journal of the American Society of Horticultural Sciences 121, 164-168.
  2. Bolda, M., 2012. Albino strawberry fruit. Strawberries and Caneberries. University of California Agriculture and Natural Resources Blog.
  3. California Plant Health Association, 2002. Western Fertilizer Handbook 9th edition. Interstate Publishers, Inc.
  4. Haifa, 2012. Nutritional recommendations for strawberry.
  5. Hart, J., Righetti, T., Sheets, A., Martin, L.W., 2000. Strawberries (Western Oregon – West of Cascades). Oregon State University Extension Service Fertilizer Guide FG 14.
  6. Hartz, T.K., 2011. Establishing nutrient diagnostic standards for high-yield strawberry production. California Strawberry Commission Annual Production Research Report 2010-2011. pp. 41-50.
  7. Hartz, T.K., 2012. Establishing nutrient management practices for high-yield strawberry production. California Strawberry Commission Annual Production Research Report 2011-2012.
  8. Hochmuth, G. and Cordasco, K., 2009. A summary of N and K research with strawberry in Florida. University of Florida Extension Publication HS752.
  9. Kaya, C., Kirnak, H., Higgs D., 2001. An experiment to investigate the ameliorative effects of foliar potassium phosphate sprays on salt-stressed strawberry plants. Australian Journal of Agricultural Research 52, 995–1000.
  10. Khayyat, M., Vazifeshenas, M.R., Rajaee, S., Jamalian, S., 2009. Potassium effect on ion leakage, water usage, fruit yield and biomass production by strawberry plants grown under NaCl stress. Journal of Fruit and Ornamental Plant Research 17, 79-88.
  11. Locascio, S.J., Saxena, G.K., 1976. Effects of potassium source and rate and nitrogen rate on strawberry tissue composition and fruit yield. Proceedings of the Florida State Horticultural Society 80, 173-176.
  12. Martinez Barroso, M.C., Alvarez, C.E., 1997. Toxicity symptoms and tolerance of strawberry to salinity in the irrigation water. Scientia Horticulturae 71, 177-188.
  13. Nelson, P.E., Wilhelm, S., 1957. Some anatomic aspects of the strawberry root. Hilgardia 26, 631-642.
  14. Penn State Cooperative Extension, 2013. The Mid-Atlantic Berry Guide, 2013–14. Chapter 6: Strawberries. pp. 49-114.
  15. Strik, B.C., 2013. Nutrient management of berry crops in Oregon.
  16. Tanji, K.K., Kielen, N.C., 2002. Agricultural drainage water management in arid and semi-arid areas. FAO Irrigation and Drainage Paper 61. FAO, Rome.
  17. Ullio, L., 2010. Strawberry fertiliser guide. State of New South Wales Primefact 941.
  18. Ulrich, A., 1976. Plant tissue analysis as a guide in fertilizing crops. In: Reisenauer, H.M. (Ed.). Soil and Plant-Tissue Testing in California. University of California Cooperative Extension Bulletin 1879. pp. 6-8.
  19. Ulrich, A., Mostafa, M.A.E., Allen, W.W., 1992. Strawberry deficiency symptoms: A visual and plant analysis guide to fertilization. University of California, Division of Agriculture and Natural Resources. Bulletin 1917.
  20. Weaver, J.E., Bruner, W.E., 1927. Root development of vegetable crops. McGraw-Hill Book Company, Inc., NY. 351 pp.
  21. Welch, N.C., Quick, J., 1981. Fertilizing summer-planted strawberries in California’s Central Coast. California Agriculture 35(9), 26-27.
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