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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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Garden Checklist for week of April 21

This week there’s plenty to keep gardeners busy. With no rain in the immediate forecast, remember to irrigate any new transplants.

* Weed, weed, weed! Get them before they flower and go to seed.

* April is the last chance to plant citrus trees such as dwarf orange, lemon and kumquat. These trees also look good in landscaping and provide fresh fruit in winter.

* Smell orange blossoms? Feed citrus trees with a low dose of balanced fertilizer (such as 10-10-10) during bloom to help set fruit. Keep an eye out for ants.

* Apply slow-release fertilizer to the lawn.

* Thoroughly clean debris from the bottom of outdoor ponds or fountains.

* Spring brings a flush of rapid growth, and that means your garden is really hungry. Feed shrubs and trees with a slow-release fertilizer. Or mulch with a 1-inch layer of compost.

* Azaleas and camellias looking a little yellow? If leaves are turning yellow between the veins, give them a boost with chelated iron.

* Trim dead flowers but not leaves from spring-flowering bulbs such as daffodils and tulips. Those leaves gather energy to create next year's flowers. Also, give the bulbs a fertilizer boost after bloom.

* Pinch chrysanthemums back to 12 inches for fall flowers. Cut old stems to the ground.

* Mulch around plants to conserve moisture and control weeds.

* From seed, plant beans, beets, cantaloupes, carrots, corn, cucumbers, melons, radishes and squash.

* Plant onion sets.

* In the flower garden, plant seeds for asters, cosmos, celosia, marigolds, salvia, sunflowers and zinnias.

* Transplant petunias, zinnias, geraniums and other summer bloomers.

* Plant perennials and dahlia tubers for summer bloom.

* Mid to late April is about the last chance to plant summer bulbs, such as gladiolus and tuberous begonias.

* Transplant lettuce seedlings. Choose varieties that mature quickly such as loose leaf.

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