Incidence of Bactericera cockerelli (Hemiptera: Triozidae) Under Different Pesticide Regimes in the Lower Columbia Basin.

Zebra chip is a potato disease transmitted by the potato psyllid Bactericera cockerelli (Šulc) and distributed across several regions of the United States. Because of its potentially devastating effects, the disease represents a threat to the potato production and the industry particularly in the Pacific Northwest, where it was first detected in 2011. Efforts to control the disease primarily focus on managing the vector using pesticides. In this study, the effectiveness of two pesticide spray programs in 2012 ("FULL" and "REDUCED") and three in 2013 ("FULL 1," "FULL 2," and "REDUCED") against the potato psyllid was evaluated. Yellow sticky cards were used to monitor the adults, whereas immatures were evaluated by sampling the leaves. Overall, the vector infestation level in both years was low. The mean total number of adults per trap in 2012 was 1.5, 5, and 12 for "FULL," "REDUCED," and the control, respectively, while in 2013 was 10.3, 20.7, 17.7, and 52 for "FULL 1," "FULL 2," "REDUCED," and the control, respectively. For each particular year, season-long regimes were most effective at controlling the pest than targeted applications; however, there was no statistical difference among regimes ("FULL" or "REDUCED") after early July, when the first psyllids were detected, until mid-August. Moreover, this number was similar to the control. Also, psyllid density was uniform across sticky traps, and no clear relationship was found between the proportion of Lso-infective psyllids and zebra chip disease intensity.