Insects multiply much faster in warm weather. Aphids and mites are two pests to watch for. Aphids (often called plant lice) are small soft bodied sucking insects usually concentrated on new growth. They are usually green, but can also be pink or black. Aphids exude a sweet juice which drips on the ground. Ants are often associated with aphids because they use the juice for food. Mites are tiny eight legged pests which suck juices almost entirely on the underside of leaves. They are especially bad on needle-leaf evergreens. Yellow and brown mottling on leaves or needles is the most common symptom. Hold a white piece of paper under affected growth and shake. You will see tiny specks which move.
Both aphids and mites can be washed off plants. A strong stream of water will wash most of them off. However, soap or detergent will do a more thorough job of removing them. You can make your own mixture using dish wash detergent. A “Syphonex” works very well for this purpose. It is an inexpensive connector placed between two hoses or between the faucet and hose. It has a rubber tube which is placed in a bucket of strong soapy water. The soapy water is siphoned into water running through the hose. With a nozzle on the end of the hose you can wash these two pests off onto the ground and they will not find their way back up onto the plants.
Neem oil is a natural pesticide that is effective in controlling aphids, mites, and many other pests. Neem oil also controls leaf diseases such as black spot and mildew. Because of its dual action, it is my favorite pesticide for roses.
Spinosad is my newest favorite natural pesticide. It is effective on a wide range of insects because of its systemic action. It gets to leaf miners and borers which other insecticides do not reach. I use Spinosad for leaf miners in leaf vegetables such as chard, spinach and lettuce. It is also very effective against cabbage worms which also invade broccoli and cauliflower heads. It is effective against cherry maggot and codling moth worms in apples and pears. Spray it on the silks of corn to prevent ear worms. It is effective against the lace bugs which cause azalea and rhodendron leaves to become mottled and then turn white.
Because it is natural and non-toxic it can be used up until a day or two before harvest. Spinosad is toxic to bees and should be applied in early morning or evening when they are not active. Look for Spinosad on line or in the organic section of full service nurseries and garden stores. Look for “spinosad” on the active ingredient list. There are several brands available from Bonide, Monterey, Green Light and Ferti-lome.
Slugs and snails are another pest which must be re-treated regularly or they eat holes in leaves of annual and perennial flowers and vegetables. They only feed at night or in high moisture conditions, so you seldom see any signs except holes and their slimy trails. Snail and slug bait lasts about 2 weeks and then must be re-applied. The most common slug baits contain mesurol. However, baits with iron phosphate are safer for use around children, pets and wildlife.