Pest Alert
Insect Alert
Hopefully your diligence against last months most wanted list, aphids, leaf miners, and whiteflies is paying off. Keep a watchful eye because they continue to pose a threat to plants.
- This month be on the lookout for an increase in the population of scale insects. There are many species of scale so they come in many shapes and sizes. They are generally ovoid in shape and often will be a color that helps them blend in with their host plant. There are soft scales with more pliable wax like outer coatings and hard scales with harder outer coatings. The insect excretes this coating to protect itself from predators. The coating also makes it resistant to many insecticides. The insect taps into the plant and extracts the sugary sap. The mobile young that hatched out earlier in the season have since hunkered down. They may be getting large enough to be noticeable At this stage I recommend against spraying as the spray may also damage beneficial insects that may control the population. Manual removal is best during the summer. This is accomplished by scraping off the scale with an old credit card, nail file or on woodier plants a non-scratching kitchen scrubbing pad. Otherwise I suggest you wait until the dormant season to spray with horticultural oil which will smother the insect within. Scale can attack many evergreens and deciduous trees and shrubs. Some examples of susceptible plants are roses, fruit trees, currants, grapes, raspberries and Euonymous.
- Damage from apple maggots will begin to become apparent this month. The flies emerge late June through July and lay eggs just below the skin of the fruit. The larvae tunnel through the fruit until it drops to the ground. The best thing to do now is to put a tarp down below the tree. Collect infected apples that fall and destroy them. This prevents the maggots from reaching the soil where they will overwinter. The larvae may live in the soil for more than one season so you may need to continue this procedure for a few years. Be prepared early next summer with Phermone based apple maggot traps to catch the flies before they lay eggs. Beneficial nematodes and neem oil drenches applied to the soil below the Apple trees may also help reduce the apple maggot larvae population.
Diseases alert
Continue to be on the lookout for Black spot, Botrytis blight and Verticillium wilt. As we move into the middle to end of summer be on the lookout for these additional diseases:
- Powdery Mildew spores have been active since the spring but the disease may only become a problem this month. This is because stressed plants are more susceptible to the disease than heathy plants. Lack of water during our dry season will stress plants. So the first line of defense is maintaining healthy plants. If the disease grabs a foothold you can spray the plants with neem oil, or a baking soda/summer oil spray. Cornell University recommends 1 tablespoon of baking soda (sodium bicarbonate), 2 = teaspoons of summer oil (a natural oil based insecticide used on plants) mixed with 1 gallon of water. Some plants you may find powdery mildew on are zucchini/squash/pumpkins, beans and peas, lilacs, roses, delphiniums, zinnias, apples, pansies, rhododendrons and azaleas, strawberries, grapes, tomatoes/potatoes as well as maples, sycamores and oaks.
- Late Blight can ruin a potato, tomato, eggplant or pepper crop faster than you can say “potato famine”. Watering methods that wet the leaves of these plants will encourage the disease. If you must water from above do it in early morning so the leaves dry as quickly as possible. Copper based fungicides work well and preliminary research has indicated that neem oil is also an effective control.
