Garden & Greenhouse July 2017 Issue - Page 44

FEATURESTORY by Nathan Jackson Identifying and Eliminating the Two-Spot Spider Mite Tetranychus urticae T he fi rst signs this pest has arrived are yel- low speckling on leaf surface. Eventually little dots on underside of leaves and fi ne webbing between leaves. Under magnifi ca- tion small eggs shaped like perfect spheres might be visible and you plants may also lack vigor. Spider Mites are probably the most well-known and common pest in existence. Most growers have en- countered them at one time or another and some growers are plagued with them crop after crop. They are tiny little pests, but can be very destructive. They suck vital juices from the plants using mouth parts which have been modifi ed to pierce the individual plant cells. As spider mites feed on the plant, they destroy the chloroplasts in the leaves. This leads to a decline in photosynthesis, the stomatas close and transpiration decreases. If left uncontrolled the plant will continue to weaken and eventually die. BioPlex ORGANICS Plant Survival SOLUTIONS • Product INNOVATION • Proprietary TECHNOLOGY • Natural SUSTAINABILITY • Good SCIENCE • Great VALUE BioPlex Organics toll free: 1-800-441-3573 email: tech support: Spider Mites usually live on the underside of the leaves. They are very small, less than 0.04 inches across or about the size of a pinhead. They have a clear to yellow color and as they grow older they get two dark spots on their back. The dark spots grow larger as they feed on more chlorophyll and plant juices. Spider Mite eggs look like perfectly clear or amber round spheres when viewed with a magnifi er. As the spider mites become more estab- lished fi ne webbing can be found stretching between leaves and covering the tops and buds of the plant. Environmental conditions greatly infl uence the Spider Mite life cycle and they thrive in hot, dry conditions. As the temperature increases, they can evaporate more moisture from their body and in turn suck more juices from the plant. In temperatures above 100 degrees, their life cycle can shorten from 3 weeks down to as little as one week from egg to adult! They can become sexually mature in 5 days with each female living up to 4 weeks and being ca- pable of laying 20 eggs per day. As those eggs hatch and the resulting mites start breeding the entire pop- ulation can explode very quickly. This is why some growers will see a couple of Spider Mites and then a week or two later their plants are covered in webs. Outdoor growers need to be aware of the Spider Mites ability to go dormant. When light hours out- doors start to drop below 12 or 13 hours per day and at the same time temperatures start to drop, Spi- der Mites can enter a "diapause" state.  Adult females discontinue feeding, mating and other normal activi- ties, and turn almost completely red in color. They search for a safe place to spend the winter. These safe places can be a crevice in a tree trunk, plant debris, or even grow equipment. They will stay in a dormant state until the next spring, and as the tem- perature warms back up they emerge to infest your new plants. One of the best ways to control mites is to take measures to prevent them from getting established on your plants. Spider Mites are very creative when it comes to fi nding their way onto plants. They can hitch a ride on a strong breeze, literally blowing in the wind onto your plants. They can also climb onto people and pets, so if you have visited other cultiva- tion sites make sure you change your clothes and www. bio-plex .com 44 July 2017