Associate Professor Utah State University Logan, Utah
Water availability for agriculture is anticipated to become increasingly constrained as a consequence of climate change. Dry conditions can promote herbivorous arthropod outbreaks in agricultural systems. Traditional IPM approaches have included increasing irrigation to agriculture fields or spraying with pesticides. The former may not be feasible during water scarcity and the latter can have a number of unintended consequences, such as hazards to people and the environment. Consequently, there has been increased investment in the development of crops capable of tolerating water-stress and in more water-efficient crop technologies. We first review our recent study on the interactions between drought tolerant crop varieties, water-stress, and spider mite (Acari: Tetranychidae) outbreaks on corn. Then, we test for interactions of crop drought tolerance, water-stress, and available irrigation technologies upon spider mites and their natural arthropod predators. Sprinkler irrigation technologies can wash arthropod pests off leaves, but the efficacy of different systems has not been thoroughly compared. We developed a field experiment using two sprinkler head irrigation technologies, mid-elevation spray application and low-energy precision application, in comparison with the surface-level mobile drip irrigation (non-sprinkler). We found that the mid-elevation spray application reduced both spider mites and larval predators. We anticipate that the height from ground and concentrated spray upon the leaf surface mediated this finding. The frequency and intensity of water-stress are predicted to become more severe in the drought-prone western US. Thus, we recommend that future efforts in IPM consider irrigation practices for balancing water availability, pest outbreaks, and maintaining arthropod predator populations.
