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These little pests love hot, dusty, dry conditions


Spider mites can quickly turn a green leaf into a speckled mess. Fight them with water! (Photos courtesy UC Integrated
Pest Management)

To fight spider mites, use water, not pesticides



These itsy-bitsy spider cousins are making a mess.

Recent hot weather has brought out the spider mites, tiny arachnids that attack a wide range of edible and ornamental plants. Right now, they’re really going after roses, covering the underside of leaves with white webs and sucking the life out of foliage.

According to the UC Cooperative Extension master gardeners, spider mites also attack many fruit trees, vines, berries, vegetables and other ornamental plants. Look for the telltale webbing.

The spider mites themselves are teeny-tiny, no bigger than the period at the end of this sentence. When shaken from a leaf onto a sheet of paper, they look like fast-moving dots.

They love hot, dry, dusty conditions. May’s early heat wave brought them out in force. They can multiply quickly, producing a whole generation in a week. If left undisturbed, they can overwhelm plants. They’re especially bad during drought conditions and can do the most harm to water-stressed plants.

The key to their control? Water. By keeping plants well hydrated and dust down, spider mites are a lot more manageable. In addition, they have many natural predators in the garden. By August, the good guys usually can keep the spider mite population in check.

Unless you apply a broad spectrum pesticide. That kills the good bugs while leaving the spider mites free to weave their webs of destruction.
This is an advanced case of spider mite damage.

Besides attacking roses, spider mites can cause fruit trees to lose their leaves in spring and early summer. The damage at first looks a little like peach leaf curl with foliage developing stipples and turning yellow or red before falling off. Except spider mites attack a lot more than peaches and the fallen leaves usually show signs of that white webbing.

In the vegetable garden, they attack the leaves of squash and melons, potentially leading to sunburn. They also like beans, munching the pods as well as leaves.

Early signs of spider mite damage are stippling and yellowing of leaves. Turn a suspect leaf over and look for the white webbing. Remove and dispose of that infested leaf. Then, spray the bush with water, washing dust off leaves (along with some spider mites, too).

Insecticidal soap also can be effective in nipping a spider mite infestation in the bud. Make sure to spray the underside of leaves.

For more tips and details, see the UC IPM pest notes on spider mites:
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html

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Dig In: Garden Checklist

For week of Nov. 26:

Concentrate on helping your garden stay comfortable during these frosty nights – and clean up all those leaves!

* Irrigate frost-tender plants such as citrus in the late afternoon. That extra soil moisture increases temperatures around the plant a few degrees, just enough to prevent frost damage. The exception are succulents; too much water before frost can cause them to freeze.

* Cover sensitive plants before the sun goes down. Use cloth sheets or frost cloths, not plastic sheeting, to hold in warmth. Make sure to remove covers in the morning.

* Use fall leaves as mulch around shrubs and vegetables. Mulch acts as a blanket and keeps roots warmer.

* Stop dead-heading; let rose hips form on bushes to prompt dormancy.

* Prune non-flowering trees and shrubs.

* Clean and sharpen garden tools before storing for the winter.

* Brighten the holidays with winter bloomers such as poinsettias, amaryllis, calendulas, Iceland poppies, pansies and primroses.

* Keep poinsettias in a sunny, warm location – and definitely indoors overnight. Water thoroughly. After the holidays, feed your plants monthly so they’ll bloom again next December.

* Rake and remove dead leaves and stems from dormant perennials.

* Plant spring bulbs. Don’t forget the tulips chilling in the refrigerator. Daffodils can be planted without pre-chilling.

* This is also a good time to seed wildflowers and plant such spring bloomers as sweet peas, sweet alyssum and bachelor buttons.

* Plant trees and shrubs. They’ll benefit from fall and winter rains while establishing their roots.

* Set out cool-weather annuals such as pansies and snapdragons.

* Lettuce, cabbage and broccoli also can be planted now.

* Plant garlic and onions.

* Bare-root season begins now. Plant bare-root berries, kiwifruit, grapes, artichokes, horseradish and rhubarb.

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