A. First of all, properly fed plants tend to be less troubled by aphids. Too much nutrient can be as bad as too little and high nitrogen levels have been found to encourage several aphid species.
These
insects suck juices, causing puckered or curled leaves, stunted growth, or
deformed buds and flowers. They also transmit plant disease. When
you start noticing any of the above symptoms listed above, check to see how
severe the damage is. If there is just a few aphids on the sweet peas, a
strong spray of water in early morning will eliminate all of the pests.
Also if there are just a few of these insects and just a few plants involved,
simply rub gently between thumb and forefinger. Some effective organic
controls for aphids would be planting nasturtiums, garlic, chives, coriander,
anise and petunias near the sweet peas. This will also keep them from
damaging neighboring plants. Some exotic sprays that you could use are
tea of larkspur, rhubarb leaf tea, tobacco tea and elder leaf tea. Aphids
are drawn to a trap made by pouring slightly soapy water into a yellow plastic
dishpan, sit the pan near the affected plant. Soapy water sprayed directly on
the plant can also eliminate the aphids, but be careful how you mix the soapy
water. Too much soap can damage the leaves, especially the new tender
leaves at the top of the plant.
Among the most efficient natural controls of aphids are the insect-eating species of ladybird beetles that in their larval and adult stages may completely destroy large aphid colonies. Next in importance are the larvae (aphid lions) and adults of green lacewings, brown lacewings and the larvae of flower flies.
Aphids may also be controlled by chemical methods. Malathion, Diazinon or dimithoate. Do not feed treated foliage to cattle. Fumigation of seed in a closed container is a good means of control.
Crop rotation is a simple way to control aphids on your sweet peas.