It is the time of year that owners of apple, cherry and pear trees should be getting ready to apply regular cover sprays of insecticide to control insects that cause wormy fruit.
Fruit tree owners should make sure they have adequate quantities of the necessary insecticide products on-hand. Also, their sprayers should be checked to make sure they are calibrated and working correctly.
Right now it looks like the first sprays for controlling codling moth and cherry fruit flies will need to be applied sometime around Mother’s Day, according to the WSU Decision Aid System (DAS).
The system uses weather data and models to predict insect emergence based on accumulated “heat units” as the weather warms in the spring.
It is a good tool, but it is hard to predict exactly when the first sprays should be applied because of the capriciousness of spring weather.
Our local Benton and Franklin Horticultural Pest and Disease Boards monitor the emergence of these insects using traps and advise home gardeners and fruit growers when it is time to spray.
Why is timing so important?
If sprays are applied too late, the pests enter and eat inside the fruit where they are protected from sprays. If applied too early, the spray will dissipate and be ineffective when the insects attack.
So if you have an apple, pear, or cherry tree, be ready to spray your trees within the next few weeks.
For more information on the control of these pests and what insecticide materials can be used for their control, contact the local WSU Extension office or go to: http://treefruit.wsu.edu/backyard-fruit-trees/
Growing in galvanized containers
Galvanized containers of all sorts are showing up for use in home decorating and gardening.
I remember a time many years ago when my brother attended a camp where a clean galvanized trash can was used for mixing a powdered fruit-flavored drink mix. A few hours later most of the campers were very sick.
Zinc poisoning was the result of a reaction between the drink mix and the galvanized metal’s zinc coating. Thankfully, all the campers recovered.
Galvanized containers should never be used for preparing, cooking, storing, or serving food. Also, fumes released when heating galvanized metal are harmful.
So, is it safe to grow fruit or vegetables in galvanized containers? Will zinc leach into the soil?
The answer isn’t clear from the available research.
Zinc from the galvanized metal will probably leach into the soil over time as it gradually corrodes, but most experts seem to feel that the amount leached doesn’t pose a risk to humans eating produce grown in the containers.
At least one study indicated that as much as 90 per cent of zinc in soil is unavailable for absorption by plant roots.
At this time, it appears that most experts do not think it is a health threat.
However, if gardeners are concerned, they can use galvanized containers for growing ornamental plants or line the inside with plastic if they use them for growing food crops.
Experts say old, rusty galvanized containers are more likely to leach zinc into the soil than newer ones.
An don’t forget, if you use galvanized containers for growing plants, be sure there are drainage holes in the bottom. If not, make some.
Marianne C. Ophardt is a retired horticulturist for Washington State University Benton County Extension.