Released: April 03, 2002

Early Fruit Disease Control in the Home Garden

MANHATTAN, Kan. – Early season disease control on several fruit crops can help to ensure a bountiful harvest.

"There are several diseases occurring this time of year,"said Ward Upham, Kansas State University Research and Extension Horticulture Response Center director. "They can be devastating to the tree and cause real problems."

Ned Tisserat, Extension horticulturist, provided a list of control tactics for spring diseases:

Peaches - Peach leaf curl causes unsightly and damaging leaf deformation, said Tisserat. Use fungicides such as chlorothalonil, lime sulfur or a copper-based product for leaf curl control.

"To control this fungus disease, make a single fungicide application before buds begin to swell," he said. "Bud swelling may already be occurring in southeastern Kansas, so don’t delay."

Fungicide applications during bloom and before harvest may be necessary to prevent fruit rots. Pick off and rake up old peach pits harboring the pathogens. Prune peaches yearly to reduce the incidence of fruit rots.

"I usually recommend waiting as long as possible to prune peaches, even up to bloom," Tisserat said. "When pruning, don’t leave large open wounds or branch stubs. If you prune yearly, the size of the branches you cut out should be relatively small."

Apples - Remove dead or weak limbs anytime before bud break. Prune out overlapping twigs or those limbs with poor crotch angles, and remove any hanging fruit. Annual pruning will help suppress many of the foliage and fruit diseases.

Carefully inspect the bark for signs of sunscald, insect borer injury or canker diseases. Apply Bordeaux mixture or another copper-based fungicide before the trees break dormancy to help suppress potential problems with fireblight. Read all precautions before mixing the fungicide, Tisserat said.

Consider early season fungicide applications for control of scab, rust and powdery mildew. Mid-April and late May are critical times to control these diseases. On susceptible varieties, apply a protective fungicide from mid-May to June at seven to 14 day intervals.

A fungicide spray schedule should be started as soon as the flower petals fall and should be continued every seven to ten days to keep a protective chemical cover on the rapidly developing leaves and fruit, said Sy Nyhart, Extension agent in Leavenworth County.

"One of the best fungicides available to home fruit gardeners for control of these diseases is myclobutanil, or Immunox," Nyhart said. "Rainy weather will also promote the development of diseases such as apple scab, powdery mildew, and cedar apple rust."

An insecticide should also be included in this mixture to prevent coddling moth, which causes wormy apples. Methoxychlor, malathion or Imidan can be used as an insecticide. Do not use carbaryl, or Sevin within 35 days of bloom as it will encourage fruit drop.

"Home fruit spray mixtures that contain captan or a copper product and an insecticide are okay for certain apple cultivars," Tisserat said. "A better choice would be to use myclobutanil, sold as Immunox. It is effective against all three apple diseases."

Organic gardeners may substitute wettable sulfur for the synthetic fungicides listed. Sulfur however, may not completely control all spring diseases and may cause significant injury to the leaves during hot weather. Periodic fungicide applications may be needed during the summer to control fruit rots.

Raspberry and Blackberry - Prune out dead or damaged canes. Apply a delayed dormant application of liquid lime sulfur to control cane diseases on raspberries. These sprays are not necessary on blackberry, Tisserat said.

New blackberries or raspberries should be checked for any galls or swellings on the roots, which may indicate crown gall.

Grapes - Prune the vines and apply liquid lime sulfur while the vines are dormant to suppress early season disease development, Tisserat said.

Suppress black rot with routine applications of triadimefon, such as Green Light Fung-Away, myclobutanil or captan starting when the new shoots begin to emerge from the vine.

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Lucas Shivers, Communications Assistant
lshivers@oznet.ksu.edu
K-State Research& Extension News