The Q&A Archives: Grubworms and cicada worm damage

Question: I am having alot of trouble with grubworms and cicada worms eating the roots of my fruit trees,roses,shrubs,everything! My question is, besides nematodes (too expensive for someone on a set income), what other effective way is there to kill them. Someone told me that using an ammonia, dishsoap, water mixture, will kill aphids and other bugs on my bushes. I haven't used it yet for fear of burning my plants. I live in New Mexico, and it is already close to 100 degrees, and it is still spring! I would think that ammonia and dish soap in this heat would burn everything. But, could spraying it on the grass at the roots of my trees and shrubs help kill the worms? Or, what other product can I use, (cost effective) to kill these little killing suckers?

Answer: It's really important to identify exactly what is damaging your plants before attempting to spray something. You may do more harm than good. Also, many beneficial insects and birds will arrive to eat pests. Spraying will kill beneficial insects as well as the "bad guys." A soapy water spray is indeed a fairly benign method of aphid control, but do NOT include ammonia! I always start with the simplest method first, and if that isn't successful, move on from there. Healthy vigorous plants will withstand insect attacks best and sometimes a little damage is acceptable. If your aphid problem is not too severe, a strong blast of water from the hose should work. Spray underneath leaves, in between, etc. Do this daily.

If that doesn't work, try a soapy water spray. Use 1 teaspoon to 2 tablespoons of liquid detergent soap per gallon of water. Use regular, not concentrated soap. Don't use soaps with lemon, as the citric acid can burn plants. Start with the lower amount and work up as needed. Spray as often as needed. As with any spray you might wish to test it on a few leaves first before you treat all your plants. Next on my list would be an insecticidal soap spray.

Ladybugs and their larvae are voracious eaters of aphids. They often "arrive" a week or two after the aphids, so not spraying with chemicals is a good idea if you'd like to attract them to your garden to consume aphids for you.

As for the grubs, again it is important to know specifically what they are. The aphid treatment is not useful for grubs. I suggest you contact your County Cooperative Extension office. They will know what the typical problems in your area are, and how best to treat them. Note than many pests are seasonal and as weather conditions change, they will disappear. Pests seek out stressed plants for attack, so the best thing you can do to prevent problems over time is to grow healthy plants with effective watering methods. Good luck!

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