Fungicide Application for Late Blight Management: A Boom Attached to a Center Pivot Irrigation System.

Chlorothalonil was applied to commercial potato fields of cvs. Russet Norkotah and Russert Burbank in replicated trials through either a center-pivot irrigation system or a spray-boom-attached-to-the-pivot system. Water rates were 26,192 and 675 liters/ha for the center pivot and attached boom, respectively.

Comparison of Application Methods on Deposition and Redistribution of Chlorothalonil in a Potato Canopy and Potential for Control of Late Blight.

The effect of application method by aircraft (fixed wing), ground, and chemigation on deposition of chlorothalonil in a potato canopy was compared over 2 years. Initial chlorothalonil deposition was greatest with ground application, less by aircraft, and least with chemigation. After application by aircraft or ground, the upper canopy had more chlorothalonil than the middle, and the lower canopy had the least.

Effects of Seedborne Potato Virus Y Infection in Two Potato Cultivars Expressing Mild Disease Symptoms.

The effects of seedborne potato virus Y (PVY) in Shepody and Russet Norkotah, two new cultivars that express mild disease symptoms, were determined by comparing tuber yield and specific gravity of plants grown from PVY-infected seed with those of adjoining plants grown from virus-free seed. Seedborne PVY-infected Shepody plants produced 28.7% less total yield in 1994, and 41.

Expansion of Potato Late Blight Forecasting Models for the Columbia Basin of Washington and Oregon.

A regional potato late blight forecasting system for irrigated potatoes in the semiarid environment of the Columbia Basin was expanded by developing specific forecasting models for four vicinities throughout the Basin. Relationships between weather and outbreaks of late blight at the locations over a 27-year period were examined using logistic regression analysis. The response variable was a year either with or without a late blight outbreak.

Role of Green Peach Aphid Flights in the Epidemiology of Potato Leaf Roll Disease in the Columbia Basin.

Three distinct and highly predictable green peach aphid (GPA) (Myzus persicae) flights that occur seasonally in the spring, summer, and fall were detected at a southern, central, and northern location in the Columbia Basin of the Northwestern United States. Intensity and timing of the flights was approximately the same at the three locations. Timing and number of alatae captured in the spring and summer flights was associated with heat unit accumulation.

Potato Late Blight in the Columbia Basin: An Economic Analysis of the 1995 Epidemic.

The cost of managing late blight in potatoes during a severe epidemic caused by new, aggressive strains of Phytophthora infestans in the Columbia Basin of Washington and Oregon in 1995 was documented. The mean number of fungicide applications per field varied from 5.1 to 6.