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Mon, Aug. 19

What’s bugging our gardens? Insects and diseases!

Leaf Spot, seen here on a tomato plant, can be treated by removing the infected leaves as they appear, then spray the entire plant with organic Revitalize Biofungicide at two-week intervals until clean growth emerges. (Watters/Courtesy)

Leaf Spot, seen here on a tomato plant, can be treated by removing the infected leaves as they appear, then spray the entire plant with organic Revitalize Biofungicide at two-week intervals until clean growth emerges. (Watters/Courtesy)

Amid lots of summer flowers in full bloom, local gardeners have started to harvest from their vegetable gardens. This is turning out to be a good garden year, but also a good year for the insects and leaf diseases that attack our beautiful plants and delicious homegrown vegetables.

Diseases and insects usually are not fatal to plants, but they can make them look ugly and reduce vegetable, fruit and flower production. As we transition into the summer growing season and the monsoons, we can stay ahead of these garden problems if we watch our gardens closely.

How to watch for them & how to treat them

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Aphids (Courtesy)

Aphids have infested this zucchini flower so that most likely the plant will not bear fruit. Spraying the flower, along with the surrounding foliage, with Triple Action is the organic solution to this organic garden problem. Repeated sprayings probably will be necessary.

Budworms enjoy the taste of flowers like petunia, geranium and calibrachoa. If your beautiful hanging baskets and container gardens are green with no flowers, their plants probably have budworms. The worm is so small that it’s really difficult to find; look for holes in each flower and caterpillar poop on the leaves. Spray the entire plant with BT (Bacillus-thuringiensis), and fertilize with Flower Power, and they should be covered in flowers in a couple of weeks.

Cabbage Worms, aka cabbage loopers, when feeding on cabbage leaves, leave holes + caterpillar poop = Yuck! They also enjoy the taste of kale, Brussels sprouts and Swiss chard. The most effective organic control is to remove green adults by hand, then spray the entire plant with BT (Bacillus-thuringiensis).

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Cucumber Beetles (Courtesy)

Cucumber Beetles eat the roots, leaves, and flowers of plants while spreading bacterial wilt disease. The spread of bacterial wilt is deadly and quick. It starts with one wilting leaf and rapidly spreads to other leaves. A telltale sign of bacterial wilt is the sticky, white sap-like substance that oozes from snapped stems. Bacterial wilt is a severe disease of cucumbers and muskmelons. The beetles are black with yellow stripes or spots. They can be controlled with Triple Action spray.

Plant Viruses — Mottled yellow leaves usually indicate a mosaic virus. Remove and destroy any affected plants as soon as possible to limit the spread of the virus.

Gray Mold, aka botrytis, is a fungus that affects roses, peonies, grapes and all berry plants. Remove and destroy any affected leaves. Spray the entire plant with organic Revitalize Biofungicide at two-week intervals until clean growth emerges. Give the plants plenty of room for airflow and cut back and remove foliage in the fall to discourage spores from over-wintering.

Leaf Spot can be seen on the lowest leaves of this tomato plant. Remove infected leaves as they appear. Prevent spores from splashing up onto the foliage by pinching off all lower leaves of each plant. Spray the entire plant with organic Revitalize Biofungicide at two-week intervals until clean growth emerges.

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Powdery mildew (Courtesy)

Powdery Mildew can turn the leaves white on vinca, roses, red tip photinia, apples, squash and many other plants. If possible, pick off infected leaves then spray with Revitalize Biofungicide at two-week intervals until clean growth emerges. Summer rains encourage the infection to spread to other plants, so prompt treatment is advisable. Follow up with 7-4-4 All Purpose Food to enhance plant growth.

Spider Mites occur naturally in juniper forests and spread to spruce, tomato, rose and other plants. The foliage is often covered in a delicate spider’s silk that causes the plant to dry out and die. Spray at two-week intervals with Triple Action until no spider webs recur. Plants will die without treatment.

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Squash Bugs (Courtesy)

Squash Bugs leave holes in the leaves of squash and pumpkin plants. Inspect damaged leaves for insects and eggs, removing them from the plants right away. Targeting the underside of large leaves, spray with Triple Action at two-week intervals until no new damage is found.

Tomato Hornworms are the larval stage of the five-spotted hawk moths aka hummingbird moths. Both phases of these insects are formidable to see, but the hornworm is not a welcome sight in the vegetable garden. Hornworms favor the leaves of tomato and pepper plants. Since hornworms blend in so well with the foliage, you might not notice them until you start to see the damage. Remove the 4-inch caterpillar by hand, then spray the entire plant with organic BT (Bacillus-thuringiensis).

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Whiteflies (Courtesy)

Whiteflies feed off plants by sucking their juices dry. They cause wilting, stunting and eventual death. Just brushing a garden leaf causes the insects to flutter into the air. If you discover a small infestation in the garden, wash them off with a blast of water with a hose or by sinking the plant into a bucket of water. Spray the underside of leaves of infected plants at two-week intervals with organic Triple Action.

Free help

If you’re not sure what is causing damage to stressed plants in your garden, the experts here at Watters Garden Center can help. Place a sample of the troublesome insect or of the ailing plant in a sealed plastic bag. Then bring the specimen(s) in for identification and advice for proper eradication. The center has a large-screen TV connected to a 200X microscope that can give an enlarged view of almost any insect, any size.

Until next week, I’ll be helping friends with garden issues here at Watters Garden Center.

Ken Lain can be found throughout the week at Watters Garden Center, 1815 W. Iron Springs Road, Prescott, or contacted through his website at WattersGardenCenter.com or FB.com/WattersGardenCenter.

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