Sacramento Digs Gardening Article
Your resource for Sacramento-area gardening news, tips and events

Articles Recipe Index Keyword Index Calendar Twitter Facebook Instagram About Us Contact Us

Some pests love hot, dry weather

Spider mites, tomato hornworms spiking now

Sacramento Digs Gardening
BY Debbie Arrington PUBLISHED AUG 31, 2020

Spider mites love hot, dry conditions. Ash and fallen leaves cling to spider mite webs covering a camellia. (Photos: Debbie Arrington)

Some of the biggest and smallest pests to attack our gardens are enjoying these last days of summer – much to our dismay. While many critters retreat in high heat, these invaders actually spike in numbers and activity as the mercury rises.

Recent dusty, hot and smoky weather has been terrible for people. Spider mites think it’s heaven. They don’t mind the ash clinging to their webs.

These itty-bitty arachnids thrive in hot, dry, dusty conditions, attacking water-stressed plants.

According to the UC Cooperative Extension master gardeners, spider mites can multiply especially rapidly during these conditions.

“If the temperature and food supplies are favorable, a generation can be completed in less than a week,” say the master gardeners’ pest notes.

No bigger than a pinpoint, a spider mite is a minute arachnid, the same eight-legged class that includes spiders and ticks.

Spider mites spin telltale webs, which are much more noticeable than the tiny creatures. They attack just about any plant, from strawberries to full-size trees, sucking out moisture.

Beneficial insects usually can outnumber the spider mites and keep them under control. But when the weather turns unusually hot, dry and smoky as it has been, the predators tend to retreat, allowing the spider mites to take hold.

The solution? Water. Take the hose and spray dust and ash off leaves, making sure to get the undersides of foliage, too. A strong shower disrupts spider mite paradise and holds them at bay until the real rains come (hopefully) in fall.

To keep them away, keep the garden well watered. Irrigation is key to spider mite control. They don’t like it wet.

Tomato hornworms will munch on leaves, stems and fruit (both

unripe and ripe) of tomato plants.

Meanwhile, the heat also brought out a late-summer surge of one of the biggest bugs in the vegetable garden: The tomato hornworm.

Natural enemies usually keep their populations under control. But hornworm numbers can spike in late summer with high heat.

Fat as a finger and just as long, hornworms rank as Sacramento’s largest caterpillars. They eat big bites out of their favorite food: Ripe tomatoes. They’ll also eat green tomatoes, leaves and stems.

Their stripes let them hide in plain sight. They blend in so well with their surroundings, they can seem impossible to spot.

If you suspect hornworms, look for their poop. They leave large black or green droppings on or around the plant. If you see those droppings, carefully inspect the plant’s leaves and stems. When you find it, pick off the hornworm and dispose of it.

If the hornworm escapes capture, it burrows into the soil and pupates into a moth of equally gigantic proportion: The hawk moth. Emerging in spring, this brown and gray moth has a 5-inch wingspan.

Rototilling the tomato bed after harvest prevents those moths from ever developing – and laying eggs next spring.

For more on spider mites: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html

For more on tomato hornworms: http://ipm.ucanr.edu/PMG/GARDEN/VEGES/PESTS/hornworm.ht ml

Comments

0 comments have been posted.

GENERAL GARDENING

An article about gardening.

Keywords:

UCCE master gardeners Sacramento pests heat wave heat stress heat pest gardening integrated pest management vegetables heat summer vegetables garden pests vegetable gardening

Newsletter Subscription

Sacramento Digs Gardening to your inbox.

Food in My Back Yard Series

May 13: Your plants can tell you more than any calendar can

May 6: Maintain soil moisture with mulch for garden success

April 29: What's (already) wrong with my tomato plants?

April 22: Should you stock up on fertilizer? (Yes!)

April 15: Grow culinary herbs in containers

April 8: When to plant summer vegetables

April 1: Don't be fooled by these garden myths

March 25: Fertilizer tips: How to 'feed' your vegetables for healthy growth

March 18: Time to give vegetable seedlings some more space

March 11: Ways to win the fight against weeds

March 4: Potatoes from the garden

Feb. 25: Plant a fruit tree now -- for later

Feb. 18: How to squeeze more food into less space

Feb. 11: When to plant? Consider staggering your transplants

Feb. 4: Starting in seed starting

Local News

Taste Spring! E-cookbook

Find our spring recipes here!

Thanks to Our Sponsor!

Sites We Like

Garden Checklist for week of May 18

Get outside early in the morning while temperatures are still cool – and get to work!

* Plant, plant, plant! It’s prime planting season in the Sacramento area. Time to set out those tomato transplants along with peppers and eggplants. Pinch off any flowers on new transplants to make them concentrate on establishing roots instead of setting premature fruit.

* Direct-seed melons, cucumbers, summer squash, corn, radishes, pumpkins and annual herbs such as basil.

* Harvest cabbage, lettuce, peas and green onions.

* In the flower garden, direct-seed sunflowers, cosmos, salvia, zinnias, marigolds, celosia and asters. Transplant seedlings for many of the same flowers.

* Plant dahlia tubers.

* Transplant petunias, marigolds and perennial flowers such as astilbe, columbine, coneflowers, coreopsis, dahlias, rudbeckia and verbena.

* Keep an eye out for slugs, snails, earwigs and aphids that want to dine on tender new growth.

* Feed summer bloomers with a balanced fertilizer.

* For continued bloom, cut off spent flowers on roses as well as other flowering plants.

* Are birds picking your fruit off trees before it’s ripe? Try hanging strips of aluminum foil on tree branches. The shiny, dangling strips help deter birds from making themselves at home.

* As spring-flowering shrubs finish blooming, give them a little pruning to shape them, removing old and dead wood. Lightly trim azaleas, fuchsias and marguerites for bushier plants.

Taste Summer! E-cookbook

Find our summer recipes here!

Taste Fall! E-cookbook

Find our fall recipes here!

Taste Winter! E-cookbook

Find our winter recipes here!