Browsing by Author "Miller, R. H."

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Biorational versus conventional insecticides – Comparative field study for managing red spider mite and fruit borer on tomato
(2014-10) Reddy, Gadi V. P.; Miller, R. H.
Tomato, Lycopersicum esculentum L. (Solanaceae), is an important crop worldwide that is grown both outdoors and under protected structures, for fresh market consumption and for processing. In the Mariana Islands, tomato is grown as an outdoor crop throughout the year. Tomatoes are attacked by a variety of pests, including the tomato fruitworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), and, in Pacific islands, the red spider mite Tetranychus marianae McGregor. These pests cause scarring, tissue damage, and aberrations in fruit shape or color, making the tomatoes undesirable for fresh market. Also, insect bodies, excretia or parts in fruits reduce their market suitability. Field trials aimed at improving management of these pests were undertaken at two locations in Guam (Yigo and Inarajan), USA in 2012 and 2013, assessing the efficacy of different biorational and conventional insecticides against T. marianae and H. armigera on tomato. At both locations, the mean percentage of mite-infested leaves and the population density of T. marianae were higher in control than in treated plots. An integrated pest management (IPM) program comprising sprays of selective insecticides (Petroleum spray oil, Beauveria bassiana, azadirachtin, and Bacillus thuringiensis), evaluated at 15, 30, 45 and 60 days after transplantation of tomato seedlings, significantly reduced the number of T. marianae-infested leaves and the density of T. marianae over plots treated with carbaryl, malathion, six applications of B. bassiana or B. thuringiensis and over both controls at both locations. Similarly, significantly lower fruit damage by H. armigera was recorded in the plots treated with the IPM program than in plots treated with carbaryl, malathion, or the control treatments at both locations. Marketable tomato yields from the plots which received with the IPM program were significantly greater at both locations than were those in the other treatments.
Field Evaluation of Petroleum Spray Oil and Carbaryl Against Tetranychus marianae (Acari: Tetranichidae) on Eggplant
(2014-03) Reddy, Gadi V. P.; Miller, R. H.
Tetranychus marianae McGregor (Acari: Tetranychidae) is a pest of several perennial crops and is widespread in the Pacific Basin, including the Mariana Islands where it was first reported. The mite is also present in the West Indies, Bahamas, southern USA, Nicaragua, Argentina, Brazil and Southeast Asia. Eggplant growers apply carbaryl 10 to 15 times against this pest during each cropping period. Some growers no longer cultivate eggplant and tomato because of uncontrollable mite infestations. Previous indoor studies have shown petroleum spray oil (PSO) to be effective against T. marianae. We therefore examined the comparative effectiveness of PSO (Sun-spray 6E®) at the rate of 5mL/liter, and carbaryl at the rate of 1.5 mL/liter, against T. marianae on eggplant at 2 locations in Guam. The mean percentages of mite infested leaves and the population densities of T. marianae at both the locations were significantly higher in control plots than in treatment plots. PSO treatments with 6 and 15 sprays more effectively reduced the number of T. marianae-infested leaves and populations of T. marianae than carbaryl treatments. Marketable yields of eggplant from PSO treated plots were significantly higher than from the other plots. We recommend 6 applications of PSO at 15, 25, 35, 45, 55 and 65 days of after transplanting for managing T. marianae on eggplant.