Horticulture April 2023 Newsletter
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Proper Vegetable Garden Planning for Disease Prevention
Warmer temperatures mean spring is right around the corner, and gardeners everywhere are ready to get plants in the ground. However, prior to planting, growers should develop a plan for this year’s vegetable garden. A thoughtful approach to garden layout and preparation can influence disease pressure as well as the overall success of the crop. Here are few areas to consider to get ahead of diseases as you make your vegetable garden plans.
Planting Site The best vegetable garden sites are sunny with adequate moisture and fertile, well-drained soil. Avoid low spots, which can worsen soilborne diseases, and shady locations, which can worsen foliar diseases. Prior to planting, it is advisable to draw a planting map. This allows consideration into site limitations and succession planting. Scale mod-els of the garden space can be drawn on graph paper, or simple maps may be made using a virtual spreadsheet (Figure 1). Choose perennial locations carefully to make tilling more convenient. Taller crops, such as sweet corn or tomatoes, should be planted on the north or west side of the garden to avoid shading shorter plants. Retain these maps from year to year and refer when planning next season.
Crop Rotation If the same garden site is used each year, avoid planting the same or closely related crops in an identical place each year. A three-year rotation is recommended, however, even a year or two out of a certain plant family can be benefi-cial. Crop rotation prevents disease-causing pathogens from building up in soil. Multiple vegetable crops are closely related and are prone to many of the same disease issues. Closely related crops are listed below.
• Tomatoes, Peppers, Potatoes, and Eggplant
• Cucumbers, Pumpkins, Squash, Watermelons, and Muskmelons
• Peas, Broad Beans, Snap beans, and Lima Beans
• Cabbage, Cauliflower, Kale, Collards, Brussels Sprouts, Broccoli, Kohlrabi, Turnips, Rutabaga, Chinese Cabbage, and Mustard
• Lettuce, Endive, and Salsify
• Chives, Garlic, Leeks, Onions, and Shallots
• Beets, Swiss Chard, and Spinach
• Carrots, Parsley, Celery, Celeriac, and Parsnip
Compost Piles
Avoid composting diseased plants or produce, since home compost piles typically do not reach temperatures high enough to kill pathogens. Accelerate the rate of decomposi-tion by turning compost piles at least once per month. Avoid adding fresh material to current compost piles, as new material will not break down in time for this season. Water should be added to very dry compost piles at turning to allow for more complete decomposition.
Gardening Apps Tech-savvy gardeners may enjoy utilizing one of the many mobile applications available for both Android and Apple platforms. Apps can be used to map out vegetable gardens and maintain records from year to year. Several apps allow users to enter information about cultivar, planting date, and plant growth. Some apps provide an estimated date for harvest from this information. A few apps have been designed to diagnose common disease and insect is-sues. However, diagnosis of plant problems can be a challenging task, even with the assistance of an app. Thus, if plant problems arise in the garden, reach out to a local County Extension Agent for assistance.
Keep Records Each garden season is like a school year, with lessons to be learned. Whether by app or a physical garden journal, keep track of disease and pest issues as they occur, to help develop strategies to prevent or manage these issues. Also include varieties grown, how they performed, and common weather patterns.
Peach Leafe Curl
Peach leaf curl results in disfigured leaves during
spring and summer; twigs and fruit may also become
infected. Successful management of peach leaf curl
begins in fall or early spring, even though symptoms
are not seen until leaves emerge.
Peach Leaf Curl Facts
-Symptoms begin to appear shortly after bloom and are
characterized by thick, folded, puckered and curled
leaves (Figure 1). Infected leaves typically exhibit a red
or purplish coloration (Figure 2). Diseased leaves develop
a powdery gray coating, turn brown, and wither
before dropping from the tree.
-Twigs and fruit may become infected.
-Repeated defoliation from this disease can increase
the sensitivity of trees to cold injury.
-Initial infection occurs in late winter or spring prior to
bud swell. There is no further spread of the disease
during the growing season.
-Rain and temperatures between 50° and 70° F are
required for infection.
-Caused by the fungus Taphrina deformans.
Management Options
A single preventative fungicide application prior to dormancy
(50% leaf drop to 100% leaf drop) or in early
spring (delayed dormant, just before bud break) often
provides sufficient management. In severe cases, both
fall and spring applications may be necessary. Homeowners
can apply fungicides that contain chlorothalonil
or copper. Always follow label directions when utilizing
fungicides.
Once the disease is present, the following management
techniques can be used.
-Thin fruit heavily to reduce stress on the tree.
-Provide good growing conditions and irrigation to reduce
tree stress.
-Replant with cultivars with an increased tolerance of
the disease, such as ‘Redhaven’ varieties.
-Fungicides will not be effective once the disease is
present.
By Kimberly Leonberger
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