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Q: I've heard there is a new pest in Missouri that is impacting fruit growers. Can you provide me with details?
Answered by Bruce Barrett, a University of Missouri Extension entomologist: A variety of fruit fly, the spotted wing drosophila, has appeared in Missouri for the first time and made its presence felt by fruit growers.
What sets the spotted wing drosophila apart from the 1,500 other types of fruit flies is the serrated ovipositor that females have. They can attack healthy fruit by cutting through the skin of the fruit and inserting their eggs.
Once the ovipositor breaks through the fruit's skin, that opens the door for fungus, bacteria and molds to enter the fruit. The developing maggots will feed on the inside of the fruit.
Infestations of spotted wing drosophila can cause significant economic impact.
There are some challenges to combating spotted wing drosophila.
They have a short life cycle, with as many as 10 generations in a growing season. So it is hard to monitor when a generation is completed because they are in various stages of development.
That makes it difficult to determine when to spray.
Once the egg is inside, it has infested the fruit, and sanitation is a big issue.
Next year we'll conduct more research-oriented projects that will help us provide some solutions to growers.
Q: Should I ever test my compost to check for herbicides or other problems?
Answered by David Trinklein, University of Missouri Extension horticulture specialist: Compost contaminated with herbicide is showing up in Missouri.
The culprit can be one of any three herbicides that have been approved for use on pastures and forage crops.
Newer versions of herbicides with active ingredients such as clopyralid, picloram and aminopyralid can pass through the digestive systems of foraging animals and arrive, unchanged, in the manure. If that manure is composted, gardeners could unwittingly introduce these plant-killing compounds into their soil.
So why not test compost before selling it? Commercial testing for these chemicals is costly. The test is between $300 and $400 per chemical.
It's not just compost. These herbicides can show up in mulch, too.
Once these herbicides have been added to the soil, through compost or mulch, there aren't many options for correcting the problem. You can remove and replace the soil, but that is expensive, labor-intensive and time-consuming.
The good news is there's a simple and inexpensive way to test for these compounds. Take green bean seeds and plant them in the compost. Green beans are sensitive to herbicide. If the seedlings come up OK, the compost is good. If they come up twisted and damaged, allow the compost to age until the herbicide breaks down.
It is important not to panic. We don't want to dissuade people from using compost and organic matter. They are the gardener's best friend when it comes to building healthy soil.