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HomeMy WebLinkAbout2003 02 12 Attached Distributed by Mike Mingea (2)Date: February 12, 2003 ATTACHED DISTRIBUTED BY MIKE MINGEA, CITY ARBORIST The Cycad ,Scale: a new pest of Sago Paim The Cycad aulacaspis scale in- sect israpidly spreading through the state of Florida. It was first detected in-the southern section of Miami in 1996 and has since spread northward reaching Semi- nole county in 2001. During the year 2002, many residents in the county have found the insect in- festing and causing serious dam- agestotheir sago palms. This in- sect may -be spread short dis- tances by wind dispersal of the unrnature stages but long distance dispersal is usually caused by transportation ofinfested plants to new locations. The Cycad scale has also been found in Hong Kong, Hawaii, and the. Cayman Islands. The insect:. Mature female scales are very small, white, 1.2 to 1.6 mm long and tend to be pear-shaped but are ofren uregu- `lar inshape innature. Mature male scales are 0.5 to 0.6 mm,long, white, and elongated in shape. They somewhat resemble the magnolia white scale, another - common scale insect, but the color of the insect body.and the eggs ofthe Cycad scale is orange, while the eggs and all stages of the magnolia. white scale are yel- low The average time from egg hatch to adultis 28 days. Females can lay more than 100 eggs which hatch in 8 to 12 days in warm weather, and they live less than 75 days. This insect is unusual due to the fact that it can feed on the roots ofts host plant at depths of up to 24 inches while .the few other scales that feed on roots of plants are mostly located near the - soil surface. Damage: The initial symp- toms of the damage appear as yellow or discolored spots, later the tissues become .brown and desiccated. Heavily infested leaves are almost completely coated with a white crust that in- cludes bodies of live and dead insects. The scale insects are more numerous on the lower part of the leaves and many times are only found on the underside of the leaves. A heavy infestation ofthe scales can kill a plant if not con- trolled-on time. The insect nat only attacks the leaves, stems and trunks but it also attacks the roots of the host plant. Even after con- trol has been achieved, the dead bodies. of the scale do not drop offeasily from the plant and give an ugly appearance to the plants. Old dead scales are not easily removed by mechanical means such as brushes orhigh-pressure water sprays. Control: The- rapid. spread and high densities of the Cycad scale suggests that it has no natu= ral enemies in our area. Much re- search isneeded tofind a biologi- calcontrolthat can keep this pest under control in anatural way. The most effective. way to control this scale insect is by spraying them with oils or a mixture ofoil-plus an insecticide: Good results have been obtained by using fish oil with water at a rate of 1 part oil to 100 parts. ofwater-. A single Cycad plant can be treated using a 1 quart hand sprayer or even a small squeeze bottle. The spray must be directed to the lower sur- faces oftheleaves and stems since there is where the insect is located. Other oils. such as petroleum- based horticultural oils have also been effective in controlling this insect. Conventional insecticides such as cygon and Imidacloprid (Merit) have also been used to control this pest. The fact that this insect can be found in the soil feeding on the roots, suggests that systemic insecticides should be used in addition to the oils to con- . trol the insects found in the soil. The number of spray applications nee-ded to control this insect is difficult. to determine,. it has been suggested that once a week oil spray applications should be used until the insect is under control. To check if scales are still alive, run your fingernail over the scale crust, living scales will give offs yellow to orange colored fluid. Old scales become infested with fizngi and fall offgradually, and after several months, the plants will be clean.