Garden & Greenhouse July 2017 Issue - Page 45

take a shower before entering your garden. Vigor- ously inspect and quarantine any new plants before you put them near the rest of your crop. There are dozens of sprays and miticides on the market that can kill Spider Mites, but after decades of use their effectiveness has diminished - and be- sides, who wants to smoke pesticide! Many states have very strict testing requirements for pesticide residue. One way to be sure you will not fail any test is to use natural predators that eat Spider Mites in- stead of sprays. Spider Mite Predators are the most common and widely used insect to control Spider Mites. In most conditions they will reproduce faster than the Spider Mites. Each Spider Mite Predator sucks the juice out of about 5 Spider Mites a day, or 20 of their eggs. Three of the more common species used are Phytoseiulus persimilis, Mesoseiulus longipes, and Neoseiulus californicus. These small mites love to eat Spider Mites and their eggs. To estimate your Spider Mite population you can count the Spider Mite adults and eggs on an average leaf. Count how many leaves you have on the plant and multiply the two numbers together. This will give you a rough estimate of how many Spider Mites you have on one plant. Then mul- tiply that by the number of infested plants to get an idea of how large your total population is and how many predators you might need to control it. Amblyseius andersoni and Amblyseius fallacis can eat both Spider Mites and Russet Mites, so they are a great choice if you are dealing with both pests at the same time. Specially constructed hanging sachets full of predators are now available with some species of predators. These sachets usually hold a few hundred predators which will reproduce inside the container, slowly releasing for 2 to 4 weeks. This is a great op- tion for prevention, and I recommend a few sachets of predators such as A. andersoni on every plant. Other predators are available in tubes filled with a media such as corn cob grit. These are applied di- rectly to the leaves and are immediately available to attack Spider Mites, making them an excellent op- tion when dealing if you are dealing with an active outbreak. If your plants have well developed flow- ers, be careful not to get the media on the flowers as it can be hard to remove and is undesirable on the finished buds. In these situations, fill small plastic containers (like 1 oz. ketchup containers) and place them strategically throughout the plant. You can also sprinkle some predator filled media onto index cards and place them in the foliage. After a few days these can be removed and discarded. Spider Mite Destroyers Stethorus punctillum are a larger mite predator related to the ladybug. They can be used in conjunction with other mite predators when Spider Mites have been difficult to control. Stethorus eat all stages of Spider Mites and can fly from one infected plant to the next. They take lon- July 2017 45