Editor’s note: Kelly R. Jackson takes questions called into his phone recently at the Christian County Extension Office and answers them in the Garden Corner column.
Question. How do I keep crabgrass out of my lawn?
Answer. Effectively avoiding problems with crabgrass (and goosegrass) begins with pre-emergence herbicides. There are many brands available for control. You should be aware that not all of these are recommended on lawns that were seeded last fall or that have been cut less than four times since seeding. Read the label before you make your purchase or you could damage your newly seeded lawn.
Combination fertilizers and pre-emergence herbicides are available and do save time but again check the label. Some pre-emergence herbicides recommend two applications for best control. The first application is usually in March but the second may not be needed until May. Why is this a problem? On tall fescue lawns applying fertilizer after April increases your risk of Brown Patch disease.
If you use a combination product this month, you may want to switch to a pre-emergence herbicide without fertilizer for your May application.
Q. I had problems with spider mites on my arborvitae last year. Will they be back this year?
A. Watch your evergreens for spruce spider mite activity in March and April. This cool season mite over-winters on host plants and will begin hatching soon. If you had an infestation last year, they will likely be back this year. Early detection is critical for control. Often the yellowing and bronzing of needles are the first signs of a problem.
To check for spruce spider mites, place a white sheet of paper under a branch and shake the branch over the paper. If mites are present, they will be the size of walking periods. If 10 or more are present per sample, treatment is recommended.
Some non-chemical treatments that can keep spider mites under control in the landscape include a forceful jet of water from a hose. This dislodges the mite while maintaining natural predators. Some beneficial predators can be purchased and released to feed on spruce spider mites.
In heavy infestations, miticides and horticultural oils can give a quick knock-down but excessive use of miticides can lead to resistance. Heavy attacks that go unnoticed may result in branch dieback or death of the plant, so monitoring is important.
Kelly R. Jackson is the Christian County Extension Agent for horticulture. He can be reached at 270-886-6328 or visit Christian County Horticulture online at www.christiancountyextension.com.