Nutrient Management for Peaches. 

 II. Identifying Foliar Deficiency 

 Symptoms During the Growing Season 



Karen I. Hauschild 



Department of Plant & Soil Sciences, University of Massachusetts 



Diagnosing nutrient deficiencies based on 

 observations of foliage and other plant parts is 

 not a perfect science. With peaches particu- 

 larly, symptoms of different elemental deficien- 

 cies can be similar and easily confused with 

 symptoms of disease or insect damage, 

 phytotoxicity, or even weather-related prob- 

 lems. Suspected deficiency must be confirmed 

 by leaf-tissue analysis. Although there is a fee 

 for this procedure, that fee is more than 

 recovered as a result of correcting the deficiency 

 or through savings from not applying 

 unnecessary materials. Leaf samples for tissue 

 analysis give the most reliable results when 

 leaves are selected just after growth stops but 

 before plants start translocating nutrients to 

 their roots for storage over the winter. For 

 Massachusetts orchardists, the optimal time 

 for sampling occurs between mid-July and mid- 

 August. For information on how to take a leaf 

 sample, contact the UMass Soil and Tissue 

 Testing Laboratory (413-545-2311), or the 

 author (413-545-5304). 



The following information is presented in 

 order to aid growers in preliminary identifica- 

 tion of nutrient deficiencies in peach orchards. 



Nitrogen (N) 



N deficiency is the most commonly observed 

 deficiency of stone fruits. Symptoms include 

 pale-yellowish to light-green leaves, beginning 

 on older leaves. Leaves may also show red-to- 

 purple spots that die and drop from affected 

 leaves, giving leaves a "shot-hole" appearance. 

 Oldest leaves may abscise. Other s3rmptoms 

 include decreased shoot and twig growth, small 

 fruit, or early leaf drop. These symptoms may 



be confused with potassium deficiency (see 

 below), X disease, or captan injury. X-disease 

 also results in "shot holing." Trees affected with 

 X-disease however, have tufts of green leaves at 

 the ends of shoot growth. Tufting is not 

 normally observed on N-deficient trees. 

 Captan can result in foliar damage on 

 susceptible cultivars. Rule out captan if it was 

 not applied or if the cultivar is known not to be 

 sensitive. 



Phosphorus (P) 



P deficiency is not commonly observed in 

 Massachusetts peach orchards. With defi- 

 ciency, older leaves appear mottled. Progres- 

 sive defoliation of older leaves occurs, and 

 stems and leaf petioles appear purple rather 

 than green. Yield and size of fruit may be 

 reduced. Aff'ected fruits are highly colored, 

 ripen early, have poor quality. 



Potassium (K) 



K deficiency is most often observed in early 

 summer on leaves in the middle of shoots. 

 These leaves become pale in color. There may 

 also be marginal browning of leaves or leaves 

 may roll inward. Reduced shoot growth and leaf 

 size often are a result of K deficiency. In 

 deficient trees, fewer flower buds are evident, 

 fruit size is small, and fruits do not color 

 normally, appearing dull or "dirty" orange. K 

 deficiency may be confused with N deficiency 

 (see above), zinc deficiency, or X disease. Zinc 

 deficiency, however, affects terminal leaves 

 rather than those in the mid-portion of the 

 shoot. Leaf spots, shot holes, and tufting are 



Fruit Notes, Volume 61 (Number 4), Fall, 1996 



