FOR RELEASE THE WEEK OF JUNE 4, 2000:
To prune or not to prune? My tomatoes seem to do just fine, but I’ve heard they might do even better if I pruned them. What should I snip off and when?
Before you pick up those pruning clippers, make sure the tomatoes you’re pruning are vine (indeterminate), not bush (determinate) types, says David Maas, University of Idaho extension educator. If you prune a determinate variety incorrectly, it will stop growing and so should your expectations of a bountiful harvest from that plant.
Vine tomatoes, however, normally respond positively to pruning. If you grow them on stakes, train them to one main stem–or, select a second main stem from a side shoot that has formed above either the first or second leaf-stem junction. Be sure to drive your wood or metal stake firmly into the soil about 1 foot deep and about 6 inches from the stem. Continue to shape the plant throughout the growing season.
If you grow your vine tomatoes inside a wire cage, you’ll only need to prune once and you can leave more stems. Maas suggests three or four.
Regardless of the tomato’s type, it’s always a good idea to remove suckers–those shoots that form from nodes between large leaves and main stems. "Removing suckers keeps the growth of the plant directed upwards and allows better light penetration to the developing fruit–which results in much better fruit quality," says Maas. "Remember to disinfect your pruning shears between cuts with a 5 percent bleach solution to prevent disease spread."
My family does a lot of barbecuing in the summer when the weather gets nice. Is it true that eating food made on the grill may cause cancer?
A recent study found that women who ate a lot of charred and grilled meat were twice as likely to develop breast cancer as women who did not, says Martha Raidl, University of Idaho extension nutrition specialist. High doses of a substance in meat called PhIP–produced when meat is cooked at high temperatures during grilling, broiling and frying–have been shown to produce tumors in the mammary glands of rats. Some experts now feel that women may want to braise, stew or bake their meats instead.
"If you really prefer grilling your meat, you might consider partially cooking it first, so it’s not exposed to flames for as long a period of time," Raidl says.
I’m growing vegetables organically this year and am wondering how I will be able to tell if they aren’t getting enough natural fertilizer. Are there key symptoms of deficiency that I should be looking for?
When it comes to making fertilizer decisions, University of Idaho extension educator Jo Ann Robbins is "still a real fan of the soil sample." Whether you are gardening traditionally or organically, you need to know what’s low in your soil before you can identify what it really needs.
According to Robbins, compost doesn’t contribute much as a fertilizer because the nutrients it adds are available to plants only very slowly. "Compost does have some wonderful water-holding, nutrient-holding and structure-building qualities," she notes.
To find out how much nitrogen, phosphorus and potassium organic fertilizers actually add, check with the Idaho State Department of Agriculture’s organics program. Its resource manual for organic certification lists analyses of several organic fertilizers. Order it for $15 from program manager Margaret Misner, ISDOA, P.O. Box 790, Boise, ID 83701-0790.
You can also have your soil tested through any of a number of Idaho private laboratories or the UI Cooperative Extension System. Contact your county extension educator for instructions and costs.
The twigs of our peach tree are wilting and dying back. What could be the problem?
Bob Stoltz, University of Idaho extension entomologist, suggests that you slice open the twigs and look for half-inch or smaller chocolate-brown caterpillars. If you find them, the problem is peach twig borers, which overwinter on peach, plum, apricot and almond trees and begin boring into the ends of twigs as the trees leaf out.
You’ll want to spray them now before the second-generation attacks your fruit, Stoltz says. He recommends Sevin, Neem or permethrin. "If you catch them at the first sign of a wilting twig, you can spray the whole tree and do a good job of control."
Later in the season, if you find shallow feeding damage around the stem-ends of your peach fruit, you’ll know that you missed a few. They won’t destroy the fruit or cause it to drop, but they will lay eggs that will hatch into twig-boring caterpillars again next year. Dormant oil helps, but it won’t control peach twig borers completely.