Background Kochia (Kochia scoparia) is a problematic weed with the ability to invade and establish itself quickly, particularly during drought years. Because kochia seeds typically die after one year, most kochia problems stem from seeds that were produced during the previous year. Kochia germinates in early spring but additional growth episodes can occur throughout the growing season, complicating its management. Nonetheless, because kochia has a short life span, problems with its growth could be reduced if seed production were prevented over the period of a single year.

A Montana farmer observed Kochia blooming in two of his 40-acre fields. The kochia bloom was the result of a dry spring, no crop competition, and an unusual mid-July rain. The crop which had been in the field was harvested a few days after the July rain, so was no longer a competitor with the weed for water. As a result of all of these conditions, the kochia was able to grow and spread quickly.

 Use of Data The farmer used IKONOS and color infrared (CIR) KODAK 240 imagery to evaluate the extent of the kochia problem in his fields. The July 26, 2001 CIR image shows the kochia bloom in the two highlighted strips (Figure 1). The strips appear red, showing signs of photosynthetic activity from the kochia weeds, rather than a green-grey color that indicates a harvested crop. The July 7, 2001 IKONOS images, taken earlier before the crops were harvested, show a homogeneous, mature crop canopy (Figures 2). The imagery successfully detected the differences in vegetative cover type between the two July dates, thereby serving as a scouting tool to direct post-harvest spraying efforts. The imagery, along with on-site observations, allowed the farmer to precisely locate the kochia invasion.

 Economic and Environmental Benefits Producers were able to assess the crop state and estimate the degree of crop stress and/or potential crop loss two months before harvest. By comparing yield maps and imagery, the two parties noticed a strong visual correlation between the low yield areas identified in the yield map and the water damaged zones delineated from imagery. The crop insurance agents were willing to compensate producers for low yield because they received documentation of yield loss risk just after the weather event actually happened.