Physical Remedies
Floating row cover
Examples:
Reemay, Agronet, Argyl P17.
Effective Against:
Leafminer, carrot rust fly, cabbage root maggot, cabbage looper, imported cabbage worm, and others.
Crops:
Annual vegetables such as spinach and beets (leaf miner), carrots (carrot rust fly), cabbage family (cabbage worms and root maggot).
Counteracts these pest(s):
When To Use:
Damage is done by the insect larvae. Netting prevents the adult from landing to deposit eggs on the plant. Floating row cover should be placed over the entire crop at seeding or transplanting. It must cover the plants for their entire lifetime. Floating row cover is generally used in the spring and summer but is not usually necessary for crops grown over the winter.
How To Use:
Cut a piece of netting larger than the area to be covered. Lay it out over the bed, leaving some slack for growth. Secure the edges by scooping a little soil onto the cloth, completely covering the edge. Anchor the fabric with rocks or other weights. It is important that there not be any openings in or under the cloth. You may raise the edge to weed or harvest, but replace the seal as soon as possible.
Benefits:
Completely non-chemical method. Highly effective. Heat trapping speeds the growth of plants. The fabric can be used for several seasons and is machine washable, though somewhat fragile.
Concerns:
Plants remain covered and out of direct view. Harvesting and weeding require removing netting and replacing it. Floating row cover is not effective if pests are already in the soil, so it is important to rotate crops each year. Not intended for ornamental plants.
Alternate Method:
Build a framework to support the cloth or buy a kit like those available at some garden stores. Floating row cover allows sunlight and water to enter, so it is not necessary to remove the cloth. In fact, the cloth acts as a greenhouse, keeping the plants warm and allowing them to grow more quickly than uncovered plants.