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Not too many years back, many Snohomish County gardeners also aspired to have a backyard orchard. Now a home orchard is a rarity. Standard fruit trees take lots of time, lots of space and give more fruit than today’s small families need.
Dwarfing rootstock and genetic dwarf varieties have solved those problems, so many of us have a fruit tree or two, even on small urban lots. Apples are probably the most popular tree fruits, followed by European plums. I have both.
I have never sprayed my trees with pesticides. This is partly because I like to garden organically and partly because I am lazy. Occasionally, I would get an apple with a codling moth “worm” in it, but the trees were mostly pest-free until the last couple of years. The dreaded apple maggot has changed all that.
A codling moth usually drills down to the core and remains there. They are easy to cut out and the rest of the apple is perfectly fine. (You just learn to eat your apples with a knife.) The apple maggot, on the other hand, tunnels around through the flesh of the apple and spoils the whole fruit.
Last year maggots got a few apples, but this year about half of them were ruined. And this year, for the first time, I have a little, cream-colored apple maggot in many of my plums. Okay, this is war!
Before launching into battle strategy, let’s review the life cycle of this beastie. The maggot in my fruit matures and drops to the ground or drops with the fruit. It buries itself beneath an inch or two of soil where it lives over the winter as a pupa.
The adult flies emerge in May or June, depending on the microclimate and how warm the spring is. They mate and the females start hunting fruit to lay their eggs in. Shortly, the maggot starts feeding and tunneling, getting us back to where we started.
Management strategies for apple maggot are varied and most are not intended for the lazy gardener.
Right now fruit is falling and we have an opportunity to break the cycle. Collecting and disposing of infested fruit every few days should reduce next year’s population. (Spread burlap bags or landscape fabric under the trees to help keep the maggots out of the soil.)
This makes sense, but the question is how you get rid of them. The best idea I have seen is to feed them to livestock. Next best is to bury them in the garden under about a foot of soil. Just don’t compost them!
Unfortunately, my neighbors have unmanaged fruit trees, so I have a nearby source for adults. Until everyone considers it their civic duty to clean up fallen fruit, I will need additional control measures.
Diazinon has been used in the past, but retail sales of diazinon for home use will end December 31, 2004. I’m not fond of spraying chemicals, so that wouldn’t have been my first choice anyway.
WSU now recommends Surround At Home Crop Protectant, a non-toxic kaolin clay spray that forms a barrier over the fruit and discourages egg-laying. It sounds good until I read that normal weathering and fruit growth require reapplication every 7-14 days for several months.
Some sources suggest bagging the fruit. Individual small fruits are wrapped in bags that prevent the fly getting to the apple. Again this sounds like too much work.
To schedule pesticide applications properly, orchardists have long used stick traps. When they get a predetermined number of flies per trap, they know it is time to spray. Many hobbyists decided that, if flies could be trapped, why bother with the pesticide?
Next month I will describe the management plan I have decided to adopt next
spring. After talking with lots of growers who have been refining their techniques
for several years, I have lots of good tips to share.
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Hortsense: Managing plant problems with Integrated Pest Management
