ABSTRACT
The aloe mite, Aceria aloinis Keifer, causes physiological and morphological alterations in species of Aloe L. We conducted three trials to evaluate the potential of various miticides for curative and preventive control of damage caused by A. aloinis. In the first trial, the efficacy of nine miticides against aloe mite damage was assessed without the removal of infected tissue in Aloe reitziiae Reynolds. Although significant reductions in the number of mites and eggs were found due to the treatments, miticide application did not reduce the amount of plant area damaged or damage severity. Once the plants are infected, the irreversible damage by aloe mite progresses. The second trial analyzed the effects of seven miticides on aloe mite damage on Aloe 'Goliath' plants in which the damaged tissue was removed. Reduced damage severity and mite number was observed in all treated plants. To determine if aloe mite damage could be prevented, the effects of six miticides with and without surfactant were tested on uninfected plants of Aloe spinosissima A. Berger in a third trial. Except for chlorfenapyr and fenazaquin, all treatments reduced plant damaged area, damage severity, and the number of mites 60 wk following three miticide applications. The severity index in the second and third trials suggested that all treated plants would be marketable. Our study demonstrated that there were miticides that were effective by contact (carbaryl), translaminar (spiromesifen), and systemic (spirotetramat) action, which can be used to cure and to prevent aloe mite plant damage alone or in combination with cultural practices.
Subject(s)
Acaricides , Aloe , Mites , Pest Control/methods , Animals , CaliforniaABSTRACT
Homalodisca coagulata (Say) is a recent introduction to California. It is known to spread a strain of the bacterium Xylella fastidiosa Wells, Raju, Hung, Weisberg, Mandelco-Paul & Brenner that induces oleander leaf scorch disease in oleander, Nerium oleander L. Oleander leaf scorch is lethal to oleander and threatens to decimate one of the most important landscape shrubs in California. Towards developing a management strategy for H. coagulata-spread oleander leaf scorch, we documented the affects of selected insecticides on H. coagulata mortality, feeding behavior, and disease transmission in a greenhouse study. Oleanders treated with fenpropathrin, fenpropathrin + acephate, and imidacloprid caused significant mortality to caged H. coagulata within 4 h of exposure. Within 24 h, these pesticides caused nearly 100% mortality 3 wk after treatment. In other experiments, acetamiprid and fenpropathrin treatments reduced time spent feeding and total time on plants. H. coagulata on fenpropathrin-, acetamiprid-, and imidacloprid-treated oleander died in less than 13 min on average. Oleander leaf scorch transmission by H. coagulata was blocked by applications of foliar-applied acetamiprid, and soil-applied imidacloprid and thiamethoxam.
