Sampling and Treatment Thresholds for Spider Mite Management in Field-grown Rose Plants

Spider mites [including Tetranychus pacificus McGregor (Pacific mite) and T. turkestani Ugarov & Nikolski (strawberry mite)] are the most important invertebrate pests of the roses (Rosa hybrida) grown in Kern County, Calif. (the major production area in the United States). However, sampling methods and treatment thresholds have been subjective. A rapid presence–absence field sampling method has been developed, and treatment thresholds for mites have been evaluated based on the method. Roses exhibit a higher tolerance for spider mite populations than previously thought.

GENOTYPIC AND ENVIRONMENTAL EFFECTS ON CARBOHYDRATE DISTRIBUTION IN POTATO

Field studies were conducted at two Texas locations: Lubbock, near the major production area for Texas potatoes, and College Station which is hotter and more humid. Early and late plantings were established at each location to compare cool and hot growing conditions. Nine genetically diverse cultivars, including those previously reported to be heat resistant or susceptible, were used in this study. Results indicated that the distribution of soluble carbohydrate and starch differed significantly among plant parts. In leaves and stems, glucose and fructose were the major soluble carbohydrates, while sucrose was the major soluble carbohydrate in tubers. Total soluble carbohydrate and starch content in leaves, stems and roots from the early plantings were significantly higher than those from the late plantings. Inositol increased significantly in the College Station late stress environment.