Winter Pest Management in Backyard Deciduous Fruit Trees
All deciduous fruit trees are susceptible to insect and disease problems affecting fruit quality and tree health. The best time to manage several of these pest and disease problems is during the winter dormant period, which occurs after leaves fall but before buds begin to break open in the spring.
Key management practices at this time of year are:
• Pruning to remove dead, diseased, and broken branches, promote vigor, open the canopy to sun, and improve air circulation;
• Sanitation to remove mummified fruit on the tree and diseased wood, fruit and leaves from the ground;
• Applying dormant sprays to control pests, and limit infection and prevent the spread of certain diseases. Pruning The absence of leaves in winter provides a clear view of the framework of the tree and the opportunity to thin (completely remove) or head (cut back) any branches. The amount of dormant pruning will be less if fruit trees receive appropriate summer training and pruning. For pest and disease control, prune out any dead, diseased, crossed, or broken branches as well as water sprouts and root suckers. Remove and destroy all diseased wood. Sanitation Sanitation is necessary to prevent disease and pests and reduce the need for sprays. If possible, rake and dispose of all leaves after they drop and before the first rains. Remove and destroy over-wintering fruit (mummies) in the tree and on the ground to eliminate sources of insects and diseases the next season.
Dormant or Delayed Dormant Sprays
Dormant sprays or delayed dormant sprays are generic terms for applications of pesticides applied when trees are dormant or just coming into bud swell. Pesticides include organic or inorganic fungicides, insecticides, and pesticide (horticultural) oils.
Dormant sprays provide efficient and economical treatment for a number of diseases and over-wintering pests, such as
• Scales (both armor and soft shelled scales) in many fruit tree species • Mites (eggs) in stone fruit and pears and Blister mites in pear
• Peach twig borer in apricot, nectarine, and peach, and sometimes plum and prune • Pear psylla in pears • Aphid eggs in many fruit tree species
• Leaf curl fungus in nectarine and peach
• Shot hole fungus in apricot, nectarine, and peach
The most common fungicide used in the home orchard is a copper spray, but other synthetic sprays are readily available. The natural product spinosad is considered an organic insecticide and is added to some dormant oil sprays to control more insects like peach twig borer, naval orange worm, and oriental fruit moth. Oil sprays refer to “highly refined horticultural oils” including insecticidal oils, narrow range, supreme or superior type oils. Follow label precautions regarding tree species and specific timing to temperatures, moisture, and tree stress.
Dormant sprays may not always be needed. For some insect pests and diseases, one dormant application may be adequate with good spray coverage. For other problems and depending on pest pressure, up to 3 applications may be necessary for good control. Decide, if, and how many applications, you need to apply by noting the amount of insect and disease pressure during the previous growing season.
For more information about fruit tree pruning and pest management
download the article: https://anrcatalog.ucanr.
edu/pdf/8368.pdf. There are general recommendations for types of fruit trees and a list of useful references. For detailed information about specific pests download a Pest Note from the UC Integrated Pest Management website. The most common disease problem in our area is Peach Leaf Curl. http://ipm.ucanr.edu/ PMG/PESTNOTES/PN7426. html. The following link takes you to the UC IPM fruits and nuts page. http://www.ipm.ucdavis. EDU/PMG/GARDEN/FRUIT. html. Choose the type of fruit tree in your garden and you are on your way to accessing information. There is also cultural information that offers tips on how to prune very young and mature fruit trees. The Tulare-kings County Master Gardeners will be available to answer your questions: Visalia Farmer’s Market1st & 3rd Saturdays, 8-11 am, 2100 W. Caldwell Ave (behind Sears Building)