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Catch codling moths early

Apple with codling moth frass
Look for the telltale frass, as seen on this Granny Smith. Remove that apple and eliminate a codling moth larvae, too. (Photo: Debbie Arrington)

This pest attacks apples, pears, walnuts

If you've ever bitten into an apple and found a little pink worm, you've encountered codling moths.
That worm is the moth's very hungry larva. It tunnels through the apple's flesh, creating ugly brown scars.

Eventually, the apple -- or the larva -- falls to the ground, where the moth continues its life cycle.

Codling moths love apples but also attack pears and English walnuts. Their damage is becoming very visible now.

Notice any odd holes on the side of baby apples? The holes may be topped by little brown piles. That's frass, reddish-brown droppings from the larva as it bores into the fruit.

If left uncontrolled, codling moths can infest 20% to 90% of a tree's fruit. Late-developing varieties tend to be hardest hit.

Codling moths can have three or four generations a year. In Sacramento, we're likely on generation 2. According to the UC Cooperative Extension master gardeners, codling moths overwinter as full-grown larvae in silky cocoons wedged under the tree's bark. The adult moths emerge in April. They start mating when temperatures reach 62 degrees at sunset, the only time they're active.

That makes these moths hard to trap or fight with pesticides.

The best ways to limit codling moth damage are sanitation and exclusion, say the master gardeners.
Sanitation means picking up and discarding fallen fruit. Check your tree every two weeks and look at the developing fruit. Remove and destroy any infested fruit showing frass holes; the larvae is still inside. That will cut down the next generation. That thinning has the added benefit of encouraging remaining fruit to grow bigger.

Bagging the baby fruit can exclude the moths and larvae. It's tedious and nearly impossible with a large tree but very effective especially on smaller trees. Master gardeners suggest using paper lunch bags. Cotton bags with string ties also work.

Trapping can reduce populations on isolated trees, but isn't a reliable way to reduce damage, say the master gardeners.

Because codling moths can get around, enlist neighbors with apple, pear or walnut trees to fight moths, too. That can help reduce their toll and increase everyone's harvest.


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Dig In: Garden Checklist

For week of March 26:

Sacramento can expect another inch of rain from this latest storm. Leave the sprinklers off at least another week. Temps will dip down into the low 30s early in the week, so avoid planting tender seedlings (such as tomatoes). Concentrate on these tasks before or after this week’s rain:

* Fertilize roses, annual flowers and berries as spring growth begins to appear.

* Knock off aphids with a strong blast of water or some bug soap as soon as they appear.

* Pull weeds now! Don’t let them get started. Take a hoe and whack them as soon as they sprout.

* Prepare summer vegetable beds. Spade in compost and other amendments.

* Prune and fertilize spring-flowering shrubs after bloom.

* Feed camellias at the end of their bloom cycle. Pick up browned and fallen flowers to help corral blossom blight.

* Feed citrus trees, which are now in bloom and setting fruit.

To prevent sunburn and borer problems on young trees, paint the exposed portion of the trunk with diluted white latex (water-based) interior paint. Dilute the paint with an equal amount of cold water before application.

* Cut back and fertilize perennial herbs to encourage new growth.

* Seed and renovate the lawn (if you still have one). Feed cool-season grasses such as bent, blue, rye and fescue with a slow-release fertilizer. Check the irrigation system and perform maintenance. Make sure sprinkler heads are turned toward the lawn, not the sidewalk.

* In the vegetable garden, transplant lettuce and kale.

* Seed chard and beets directly into the ground.

* Plant summer bulbs, including gladiolus, tuberous begonias and callas. Also plant dahlia tubers.

* Shop for perennials. Many varieties are available in local nurseries and at plant events. They can be transplanted now while the weather remains relatively cool.

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