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Some pests love hot, dry weather

Spider mites, tomato hornworms spiking now

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 hornworm on leaf
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

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Flowers in My Back Yard Series

Sept. 15: Plant seeds soon for fragrant spring blooms (sweet peas) 

Sept. 8: A must for fall gardens, asters are little powerhouses

Sept. 1: Yarrow an easy-care, sturdy flowering plant

Aug. 25: Crape myrtles, Sacramento's unofficial tree of summer

Aug. 18: Pollinators adore scabiosa, aka pincushion flower

Aug. 11: Hardy hibiscus adds big tropical impact

Aug. 4: Dianthus a deceptively hardy flower

July 28: Naked Ladies put on summer show

July 21: Thank Luther Burbank for these long-lasting beauties (Shasta daisies)

July 14: How to keep hydrangeas happy

July 7: Grow these bright cosmos for bees and butterflies

June 30: Agapanthus adds blue fireworks to the garden

June 23: Easy-care gazanias fill those hot corners

June 16: Daylilies are perfect for water-wise gardens (and a lot more)

June 9: Grow coneflowers for pollinators -- and yourself

June 2: Sunflowers capture Sacramento's summer attitude

May 29: Are your roses going 'blind'?

May 26: Zinnias are the summer flowers every garden needs

May 19: Plant dahlias now for late-summer flower power

May 12: Know your coreopsis from your bidens

May 5: Mums the word on Mother's Day weekend

April 28: Majestic Matilija poppy is worth a look

April 21: Celebrate roses, America's favorite flower

April 14: Small flowers with outsized impact

April 7: Calendulas do double duty

April 3: Make Easter lilies last for years to come

March 31: In praise of a pollinator magnet (small-leaf salvias)

March 24: Azaleas brighten shady spots

March 17: The perfect flower for beginners? Try zonal geraniums

March 10: Keep camellias happy for years to come

March 3: Fruit tree blossoms are a fleeting joy

Feb. 27: Are your roses looking rusty?

Feb. 24: Treasure spring daffodils now and for years to come

Feb. 17: How and why to grow wildflowers

Feb. 10: Let's talk Valentine's Day roses

Feb. 3: Why grow flowers?

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Taste Summer! E-cookbook

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Find our summer recipes here!

Garden checklist for week of Sept. 13

Now is the time to plant for fall. The warm soil will get these veggies off to a fast start.

* Keep harvesting tomatoes, peppers, squash, melons and eggplant.

* Compost annuals and vegetable crops that have finished producing.

* Cultivate and add compost to the soil to replenish its nutrients for fall and winter vegetables and flowers.

* Fertilize deciduous fruit trees. Make sure to deep water before and after feeding.

* Plant onions, lettuce, peas, radishes, turnips, beets, carrots, bok choy, spinach and potatoes directly into the vegetable beds.

* Transplant cabbage, broccoli, kale, Brussels sprouts and cauliflower as well as lettuce seedlings.

* Sow seeds of California poppies, clarkia and African daisies.

* Transplant cool-weather annuals such as pansies, violas, fairy primroses, calendulas, stocks and snapdragons.

* Divide and replant bulbs, rhizomes and perennials.

* Dig up and divide daylilies as they complete their bloom cycle.

* Divide and transplant peonies that have become overcrowded. Replant with “eyes” about an inch below the soil surface.

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Taste Spring! E-cookbook

Strawberries

Find our spring recipes here!

Taste Fall! E-cookbook

Muffins and pumpkin

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Taste Winter! E-cookbook

Lemon coconut pancakes

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Food in My Back Yard (FIMBY) Series

Lessons learned during a year of edible gardening

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Is edible gardening possible indoors?

Hints for choosing tomato seeds

Starting in seed starting

Why winter is the perfect time to plant fruit trees

When to plant? Consider staggering your transplants

How to squeeze more food into less space

Potatoes from the garden

Plant a fruit tree now -- for later

Win the weed war by tackling them in winter

Tips for planting bare-root trees, shrubs and vegetables

Time to give vegetable seedlings some more space

Ways to win the fight against weeds

FALL

Add asparagus to your edible garden

Soggy soil and what to do about it

Plant artichokes now; enjoy for years to come

It's late November, and your peach tree needs spraying

What to do with all those fallen leaves?

Prepare now for colder weather in the edible garden

Plant a pea patch for you and your garden

As citrus season begins, advice for backyard growers

Change is in the autumn air 

We don't talk (enough) about beets

Fava beans do double duty

Seeds or transplants for cool-season veggies?

How to prolong the fall tomato harvest 

SUMMER

Time to shut it down? 

How to get the most out of your pumpkin patch

Summer-to-fall transition time for evaluation, planning

To pick or not to pick those tomatoes?

: Put worms to work for you

Grow food while saving water

Enhance your food with edible flowers

Why won't my tomatoes turn red?

A squash plant has mosaic virus, and it's not pretty

Does this plant need water?

 Tear out that sad plant or baby it? Midsummer decisions

How to grow summer salad greens

 Weird stuff that's perfectly normal

SPRING

Help pollinators help your garden

Battling early-season tomato pests

Make your own compost

Where are the bees when you need them?

How to help tomatoes thrive on hot days

Your plants can tell you more than any calendar can

Maintain soil moisture with mulch for garden success

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

Should you stock up on fertilizer? (Yes!)

Grow culinary herbs in containers

When to plant summer vegetables

Don't be fooled by these garden myths

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