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Here is the weather report for your plants: One day the weather is over 60 degrees. That night, it drops to below freezing and within a few days it turns much colder with snow. If you are confused, think of how they are doing.
As humans, we respond very well to clocks and calendars. Plants, on the other hand, do not. Their biological clocks respond to temperature, day length and other stimuli. Insects and diseases likewise respond to these same factors.
That means their development varies greatly, depending on the weather. Some years, they develop prematurely and attack early. Other years, their development is later, so problems show up after they would normally be present.
There is a very logical reason for this. Pests develop on specific plant tissues. For example, it would make little sense for a leaf disease to attack a plant before the leaves are present, a flower disease to attack before the flowers are blooming and a fruit disease could not develop unless it had fruit to feed on.
For this reason, it is important to learn to read your plants. That way you can tell the specific time when you need to intervene and apply a preventive treatment. This is particularly important in the early spring, when plants develop quickly or slowly, depending on the weather.
One of the most common preventive sprays for fruit and ornamentals is the delayed dormant spray. This spray helps control the overwintering eggs and adults of spider mites, aphids and scale insects. It does nothing to control pests that attack later in the season, including cherry fruit fly and codling moth.
A pest control reference typically will say, "Apply this spray when stone fruit trees and related ornamentals including flowering plums are at pink stage." On apples and pears and flowering crab apples and pears, the instructions differ slightly. These trees specify they are to be sprayed at the "green tip stage."
The major difference is that on stone fruit trees, flower blossoms come first and then the leaf buds emerge. On the apples and pears, the leaves come out first and are followed by the blossoms.
If you are not familiar with stage development, you are now scratching your head. The typical response is, "Tell me what day I should put this on." You are out of luck because of the variable weather and the variable microclimates within individual landscapes and neighborhoods.
To help make your job easier, Utah State University Extension Service has an excellent website available for your free access. It contains several resources that will help you grow high-quality, pest-free fruit in your home orchard.
According to their website, "Utah Pests" is a group of Extension entomologists (insect specialists) and plant pathologists (disease specialists) that helps to solve the thousands of plant pest issues that concern Utah citizens every day." Start your education by going to this website: utahpests.usu.edu/.
Next, click on this web address: utahpests.usu.edu/ipm/htm/fruits/home-orchard-guide. This will take you to a gold mine of information. This online publication has 22 chapters to educate you about successful pest and orchard management practices and pesticide recommendations.
The next chapters cover pest control for each crop. These next chapters tell the effectiveness of various fungicides and insecticides and their toxicity to natural enemies and pollinators. After that are the tree fruit growth stages. These show the different growth stages so you can apply needed controls at the proper time.
The final chapters cover the pest biology and descriptions. It also lists pesticides named in the publication by both their generic and brand names to guide you as you visit local nurseries to purchase the products.
You can make the process even easier by signing up for their pest advisories. The "Plant pest advisories provide information on current pests in landscapes, fruits, and vegetables and how and when to manage them. They are delivered periodically through the growing season to your email inbox as links to an online newsletter.
"Utah IPM pest advisories are sent to your email address, and information on unsubscribing will be provided with each email. The Tree Fruit, Small Fruits & Vegetable, and Landscape IPM pest advisories are delivered weekly or biweekly during the growing season, and the Turf IPM pest advisory is delivered seasonally, 4-8 times/year."
There are four main advisories available to homeowners. To subscribe to them, go to utahpests.usu.edu/ipm/htm/subscriptions.
The advisories are Landscape IPM Advisory, Small Fruits & Vegetables IPM Advisory, Tree Fruit IPM Advisory and the Turf IPM Advisory.
Written by: Larry A. Sagers Horticulture Specialist Utah State University Extension Service
