From:
http://www.dirtdoctor.com/dallasnews.php?id=12&set_theme=1
Q. I have 7 acres of ground cover covering natural berms around my home. Every year I get worms on the vinca major. It spreads and covers beautifully in spite of the worms, but I cannot control them. The leaves turn brown and there are worm droppings in the center of the fold. I spray heavily with concentrated Diazinon4E
which is off the market 12/31/02
. The dead leaves eventually fall off and new growth comes out on the same stem. My yard and gardens are beautiful except for the vinca/worm problem. I have friends who have vinca and they have the same problem. I do cut the plants back in the late winter, and they come out nicely in the early spring depending on the moisture received. My acreage is in drip irrigation that does well, but it needs natural moisture help. – S.M.M., Abilene, TX
A. Stop using the toxic chemicals – as you have seen, they don’t help.
Although your problem is very common and most gardens experience this every year at this time, there is a solution. The reason the problem occurs in the first place is the stress of hot summer. Two secondary pests attach at this point. Caterpillars and fungal disease. Use cornmeal at 20 lbs. per 1,000 square feet before the disease symptoms start and release trichogramma wasps about the same time. Won’t eliminate the problem but it will make a dramatic improvement.