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As temperatures warm, watch out for aphids

Hungry pests can devour tender new growth

Aphids on green rose bud
Aphids are munching away on this tender rosebud. Don't let them get ahead of you, or they will destroy all the almost-spring growth. (Photo: Kathy Morrison)



Spring arrived early in Sacramento. So did aphid season.

Warmer temperatures bring an explosion of green growth in our gardens – and possibly masses of hungry aphids, too. These voracious insects love temperatures in the 65- to 80-degree range, and our current forecast is for several days in the high 60s and low 70s.

Just as your favorite spring flowers are opening, aphids seem to burst on the scene to spoil the show. They can overwhelm new shoots and buds on rose bushes and other plants now pushing out spring growth. They can eat up your whole cabbage patch as well as attack almost everything in the vegetable garden from beans to potatoes. They’re particularly destructive to seedlings and tender shoots. (They like fruit trees, too.)

Aphids can seem to come out of nowhere, in part because they never really go away. Our winter temperatures are mild enough that aphids can survive our cold months. Then, when temperatures start to rise, they “reappear.”

Their numbers can rise so rapidly because the adult females can produce a dozen live offspring a day without mating. And they’re ready to start birthing in about a week.

“When the weather is warm, many species of aphids can develop from newborn nymph to reproducing adult in seven to eight days,” explains the UC Cooperative Extension pest notes. “Because each adult aphid can produce up to 80 offspring in a matter of a week, aphid populations can increase with great speed.”

What can a gardener do to stop this onslaught? Get out the hose.

On sturdy plants, a strong blast of water can knock off aphids. They can’t fly and their soft bodies can’t survive the fall to the ground.

“Using water sprays early in the day allows plants to dry off rapidly in the sun and be less susceptible to fungal diseases,” advise the master gardeners.

For more tender plants, try adding a teaspoon or two of liquid soap to a quart of water and spray the aphids directly. Or use insecticidal soap, specifically made for this purpose.

Use of insecticides is not recommended; chemical sprays will wipe out the beneficial insects (and there are many species of these) that prey on aphids and help keep them under control.

Instead, monitor for aphids regularly, checking the underside of leaves as well as shoots. Also, remove weeds (especially mustard) that can serve as aphid nurseries.

To cut down on aphid problems, watch how much you feed your plants. Too much nitrogen (which prompts rapid growth) can invite an aphid army.

“High levels of nitrogen fertilizer favor aphid reproduction, so never use more nitrogen than necessary. Instead, use a less soluble form of nitrogen and apply it in small portions throughout the season rather than all at once,” say the master gardeners. “Slow-release fertilizers such as organic fertilizers or urea-based time-release formulations are best.”

Sometimes the best solution is to cover tender seedlings.

“Because many vegetables are susceptible to serious aphid damage primarily during the seedling stage, reduce losses by growing seedlings under
protective covers in the garden, in a greenhouse, or inside and then transplanting them when the seedlings are older and more tolerant of aphid feeding,” added the master gardeners. “Protective covers will also prevent transmission of aphid-borne viruses.”

And don’t forget lady beetles, especially the nymphs. They LOVE aphids. But the adults usually leave your garden after they’ve had their fill.

For more on aphids and possible controls: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html

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Garden checklist for week of April 19

After this midweek storm, start getting serious about spring gardening. Flowers are blooming about three weeks ahead of schedule. That includes weeds!

* Get ready to swing into action in the vegetable garden – if you haven’t already. As nights warm up over 50 degrees, set out tomato, pepper and eggplant transplants.

* From seed, plant beans, beets, cantaloupes, carrots, corn, cucumbers, melons,  radishes and squash; wait on pumpkins until May. 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. Late April is about the last chance to plant summer bulbs, such as gladiolus and tuberous begonias.

* Transplant lettuce and cabbage seedlings.

* 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? Give citrus trees a low dose of balanced fertilizer (such as 10-10-10) during bloom to help set fruit. Keep an eye out for ants. If leaves look yellow, your tree may need an iron boost -- apply some chelated iron fertilizer.

* 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 needs nutrition. Give shrubs and trees a slow-release fertilizer. Mulch with a 1-inch layer of compost, which helps the soil, but keep it a few inches away from trunks and stems.

* 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.

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Food in My Back Yard (FIMBY) Series

Lessons learned during a year of edible gardening

WINTER

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

Dec. 16: Add asparagus to your edible garden

Dec. 9: Soggy soil and what to do about it

Dec. 2: Plant artichokes now; enjoy for years to come

Nov. 25: It's late November, and your peach tree needs spraying

Nov. 18: What to do with all those fallen leaves?

Nov. 11: Prepare now for colder weather in the edible garden

Nov. 4: Plant a pea patch for you and your garden

Oct. 27: As citrus season begins, advice for backyard growers

Oct. 20: Change is in the autumn air 

Oct. 13: We don't talk (enough) about beets

Oct. 6: Fava beans do double duty

Sept. 30: Seeds or transplants for cool-season veggies?

Sept. 23: How to prolong the fall tomato harvest 

SUMMER

Sept. 16: Time to shut it down? 

Sept. 9: How to get the most out of your pumpkin patch

Sept. 2: Summer-to-fall transition time for evaluation, planning

Aug. 26: To pick or not to pick those tomatoes?

Aug. 19: Put worms to work for you

Aug. 12: Grow food while saving water

Aug. 5: Enhance your food with edible flowers

July 29: Why won't my tomatoes turn red?

July 22: A squash plant has mosaic virus, and it's not pretty

July 15: Does this plant need water?

July 8: Tear out that sad plant or baby it? Midsummer decisions

July 1: How to grow summer salad greens

June 24:  Weird stuff that's perfectly normal

SPRING

June 17: Help pollinators help your garden

June 10: Battling early-season tomato pests

June 3: Make your own compost

May 27: Where are the bees when you need them?

May 20: How to help tomatoes thrive on hot days

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