Controlling Plant Pests And Insects
Plant pests are grouped according to whether they chew plant parts, or pierce them and suck out vital juices. The chewers include many kinds of beetles, caterpillars, and worms, and also the cricket, leaf miner, leaf roller, leaf tier, millipede, roach, sawfly, slug, and weevil. Some eat into leaf edges, others make small holes in the leaf; some skeletonize a leaf, leaving only a framework of stem and veins; some eat the whole leaf, stem and all.
Some of the sucking insects (white fly and lace bug) remove chlorophyll or vital juices, leaving the leaf mottled or stippled with discolored streaks or spots. Others (scale, thrip, leaf miner, stem nematode, leaf hopper, leaf roller, mite) cause leaves to be both discolored and deformed – puckered, wrinkled, curled, distorted.
Lead arsenate is a stomach poison for chewing insects used years ago. The pest bites off a plant part covered with it, swallows, and succumbs. For sucking insects, nicotine sulfate and summer and dormant oil sprays are specific contact poisons that cover the body and enter by way of the breathing pores.
Most modern insecticide mixtures contain both stomach and contact poisons, and have some additional effect from action of poisonous vapor. Some of these ingredients some current and some now off the market (which by law are required to be listed on the label) are: DDT, malathion, rotenone, lindane, chlordane, pyrethrum, endrin, dieldrin. Parathion is another, but it is very poisonous to humans and is used by experts with extreme care.
Mites are a distinct type of sucking insect, in a number of different variations – broad mite, cyclamen mite, red spider or two-spotted mite. Among the better-known miticides are Aramite, dimite, Kelthane, Tedion, and ovex.
For some critters, particularly the repulsive slugs and snails, the most effective control is by use of bait made of some substance which appeals to their appetite mixed with poison. For others there are repellents that do not poison but are so disagreeable the insects keep away.
Among the lower forms of animal life is the nematode (leaf, stem, root-knot) against which specific nematicides are a fairly recent discovery. Sodium selenate used as a soil drench or in capsule form is a systemic poison absorbed by the plant from the soil. The plant then becomes poisonous to insects that eat on it.
Some insects – aphids and mites are a common example – develop immunity to poison over a period of time. A spray may be giving you complete control, then suddenly or gradually become ineffective. Switching to another preparation often solves the problem for a while.
Discover 100’s of Topics – 1000’s of Articles at Plant-Care.com for example: