Growing fruit crops in the home garden can be a rewarding experience and a source of enjoyment for many years.
It can also be a disappointing venture and a source of frustration. The difference is most often due to the many diseases and insect pests that attack fruit crops and in understanding how to best avoid or reduce the damage, they cause.
Some problems are minor, but others have the potential to destroy the entire crop or to kill the plants. Resistant cultivars reduce some losses and good cultural practices reduce others, but some use of chemical pesticides may also be necessary to ensure an abundant crop of wholesome fruit.
The pesticide issue is important to everyone. Pesticides are used to kill pests such as insects, fungi and weeds, and as such are poisons. However, it is important to recognize that many common household products such as bleach, ammonia and drain cleaner are very poisonous to humans, but are safe when used properly and help improve our quality of life.
When chosen carefully, used only when needed and, then, only in strict accordance with the label instructions, pesticides can provide excellent control of insects and diseases with only minimal and short-term effects on the environment.
If you choose to use pesticides, you must also accept the responsibility for their proper use, storage and disposal. If you choose not to use pesticides, more attention must be paid to the choice of crops, disease-resistant cultivars and good cultural management tactics.
As a rule, pesticides are generally less effective when used to eradicate pest populations that have become a serious problem.
However, they have proven very effective when used selectively as part of an overall pest management program.
Many home gardeners prefer not to use these conventional pesticides in favor of inorganic fungicides such as sulfur and copper compounds or botanical insecticides such as rotenone and pyrethrins.
These latter materials are also pesticides and need to be handled as carefully as the conventional materials to ensure the safety of the applicator and the environment.
As a rule, most of the botanical insecticides offer protection for only three to five days and so may need to be applied on a more frequent schedule than conventional materials.
Materials such as insecticidal soaps may appear attractive due to low toxicity to humans, but kill only on contact and have no residual activity and, thus, have very limited use against most important fruit crop pests. So, be sure to read and follow all pesticide label instructions.
The following information is intended as a guide to making decisions in controlling specific pests. The spray schedules indicate when specific pesticide applications are generally required to control various pests on susceptible varieties.
These schedules are only suggested guidelines because environmental conditions and pest populations vary greatly from year to year and location to location. Because of constantly changing pesticide registrations and formulations, application rates are not provided. It is the applicator’s responsibility to obtain the most current information on use directions and application rates directly from the pesticide label on the container.
Due to space limitations, I will only provide suggested spray schedules for Apples and Pears. For more information on fruit tree care, a few links to other publications are listed at the end of this article.
• Sanitation Measures, Apple scab, pear scab and pear leaf spot. All of these diseases overwinter on old dead leaves on the ground. Collect and destroy all leaves in the fall, including those from nearby flowering crabapples.
• Cedar apple rust. The spores that infect apple trees come from galls produced by the fungus on cedars (junipers). Where cedar apple rust is a problem, do not plant susceptible apple varieties near red cedars (junipers).
• Powdery mildew and summer rots. Prune out and destroy all dead or diseased shoots and limbs while the trees are still dormant. Mid-March is usually a good time to prune trees. As a rule, tree wound paints and dressing should not be used at the time of pruning.
• Apple maggot, codling moth and plum curculio. Fruits on the tree showing entrance or exit wounds (holes) of either the apple maggot or codling moth should be removed and destroyed immediately.
Similarly, all fruits that fall prematurely, especially during May and June, should be promptly collected and destroyed. This is an important step because it prevents developing larvae from reaching maturity and causing more damage to other fruits later in the season.
A preventive approach emphasizing early-season control of all major diseases and a number of important insect pests is recommended.
The critical time period is between bud break (green tip) and about one week after petal fall. This is the only time that certain diseases (scab, apple rust and powdery mildew) and insect pests (scales, some aphids and plant bugs) can be controlled effectively.
In other cases (scab, pear leaf spot, mites, plum curculio, pear psylla and leafrollers), a good early-season program not only provides excellent control, but also greatly reduces the potential for late-season damage and, therefore, the need for frequent sprays later in the season.
Where an early-season control program is followed, the timing of mid- to late-season sprays is much less critical and the interval between applications often can be safely lengthened to as much as two or three weeks.
For more information on fruit tree care, here are a few links to publications on Fruit Tree Care:
• Getting Started with Backyard Fruit Trees in Northern Nevada, University of Nevada Cooperative Extension, https://www.unce.unr.edu/publications/files/ho/2014/fs1414.pdf
• Backyard Fruit Trees, Washington State University, http://treefruit.wsu.edu/backyard-fruit-trees/
• Controlling Diseases and Insects in Home Fruit Plantings, Ohio State Extension, https://cuyahoga.osu.edu/sites/cuyahoga/files/imce/Program_Pages/ANR/DigIn/Controlling%20Diseases%20and%20Insects%20in%20Home%20Fruit%20Plantings%2C%20Bulletin%20780%20%28whole%29.pdf