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How to keep those worms out of your apples and pears
You might not know their names, but you’ve probably met codling moths before. Codling “moth” sounds kind of cute and fluttery; you’ve encountered it as the “worm” in your apple.
Messing with the life cycle of the codling moth
Codling moths are a serious pest for apple, pear and walnut trees. Control them by interrupting their life cycle at various points. Here’s a helpful diagram from UC Davis Integrated Pest Management that illustrates the life of a codling moth.
The egg hatches somewhere on a tree’s leaf or fruit, then the larva enters the fruit and grows. It exits the fruit to pupate in a cocoon on the ground, or in loose bark on the tree. Adult codling moths emerge to mate and lay eggs.
Stop the egg laying
Use codling moth traps to capture male moths before they can mate. Set the traps at bloom time, and hang them in the top third of your tree canopy (1 or 2 traps for a small tree, and 2 to 4 traps for a large tree). Some avid males are bound to have mated before they find the trap.
Depending on your climate, there can be several generations of codling moths each growing season. Replace the lures every 8 weeks, until you harvest your fruit and walnuts.
Make the larvae sick
Use the insecticidal virus CYD-X as a spray when the eggs are hatching. This virus will not harm beneficial insects and is listed by OMRI [Organic Materials Review Institute] as acceptable for use on organic farms.
The eggs hatch during certain temperatures and the UC Davis Integrated Pest Management site has a brand-new degree-day program you can use to determine hatching times in your orchard.
Stop the larvae from getting inside the fruit
A physical barrier will keep most of the larvae out of the fruit. Our maggot barriers are like small nylon stockings to slide on each fruit (the barrier expands as the fruit grows).
Stop the larvae from pupating over the winter
Once a larva climbs out of the fruit it will find a sheltered spot in loose bark on the tree, or in litter on the ground, and build a cocoon.
Capture the larva (now a caterpillar) as it descends, looking for a place to pupate, when you wrap “trunk bands” around the tree. Our Tanglefoot Sticky Tree Bands are ready to wrap.
Use the orchard sanitation techniques that Tricia discusses in our new video about codling moth control. In the spring—check fruit for entrance holes and discard any affected fruit; pick up and discard fallen fruit. In the fall—remove dead fruit from the tree; rake up and discard fruit and leaves.
In the large orchard
When you’re dealing with lots of fruit and nut trees, you’ll need more supplies:
* Surround, a kaolin clay powder that acts as a surface barrier on all parts of the tree
* A large number of maggot barriers
* A large amount of CYD-X virus
Check with your county Cooperative Extension office to see if you need a permit to spray the CYD-X virus and the Surround kaolin clay powder.
For more information on codling moth control, see the UC Integrated Pest Management Pest Note on the Codling Moth.
Paul HEIM Says:
Apr 15th, 2011 at 10:37 am
At what size is the apple most vulnerable? After blossom the fruits are very small.
The pheromone traps are pricey. I have 20 trees. That would mean 120 per season.
caprice rosato Says:
Apr 30th, 2011 at 7:19 pm
Are there equivalent information on degree day programs for locations outside of California? Thanks.
May 2nd, 2011 at 11:57 am
Caprice UC Davis is really excited about its new degree day information so it may be rare in other areas. Check with your local Master Gardeners (or Farm Adviser if you are a commercial farmer) through your County Extension office. Here’s a link to find them in your state: http://en.wikipedia.org/wiki/Cooperative_extension_service
May 5th, 2011 at 4:21 pm
Paul Traps alone will not prevent codling moths. Interrupt their lives at many points. The UC Davis IPM Pest Note is a good resource and they suggest bagging fruit as part of the program. Here are some of their comments:
Excellent control can be achieved by enclosing young fruit in bags right on the tree to protect them from the codling moth. This is the only nonchemical control method that is effective enough to be used alone and in higher population situations. However it is quite time consuming to apply the bags so this method is most manageable on smaller trees with fewer fruit. You may bag all the fruit on the tree or just as many fruit as you think you will need. Keep in mind that any unbagged fruit is likely to serve as a host and increase the pest population so it would be prudent to employ sanitation and mass trapping to keep the population in check.
Bagging should be done about 4 to 6 weeks after bloom when the fruit is from 1/2 to 1 inch in diameter. Prepare No. 2 paper bags (standard lunch bag size that measure 7-1/4 inches by 4 inches) by cutting a 2-inch slit in the bottom fold of each bag. Thin the fruit to one per cluster. Slip the thinned fruit through the 2-inch slit so that it forms a seal around the stem and staple the open end shut.
Oakla Oleinik Says:
Aug 26th, 2013 at 1:44 pm
My friends feed codling moth-infected apples from their tree to the neighbors’ chickens, assuming eggs and larvae will be destroyed in the birds’ digestive tract. Is this a sound assumption?
Charlotte from Peaceful Valley Says:
Sep 11th, 2013 at 11:00 am
Oakla, Yes, chickens are often used to assist in pest control and many orchardists allow them to forage for fallen fruit, and scratch beneath the drip line of their trees to help destroy soil dwelling forms and ages.
Howard Brookshire Says:
Jun 25th, 2014 at 2:39 pm
Can one wash the eggs off the leaves with a garden hose?
Stephanie Brown Says:
Jun 30th, 2014 at 8:55 am
Rubbing the eggs off would work, I doubt a hose would have enough pressure. I think it could work, but it might be challenging to find the eggs.