Summer is upon us, and temperatures in the desert are sizzling. Although the summer heat may not be appreciated by desert dwellers, it is the perfect time for soil solarization, which is accomplished by covering moist soil with clear plastic, then allowing the sun’s energy to heat soil to levels lethal to many plant pathogenic fungi. The plastic conserves soil moisture and retards heat loss. In field solarization trials conducted from 2004 to 2007 in Yuma, the average temperature of soil at a depth of 2 inches during a 1-month summer solarization period was 113°F, compared to 102°F for nonsolarized soil. The average peak afternoon temperature in solarized soil during these trials was 128°F. In these solarization trials, conducted in soil naturally infested with the lettuce Fusarium wilt pathogen, the incidence of this disease in a subsequent planting of lettuce was reduced from 42 to 91% compared to disease levels in nonsolarized plots.

To contact Mike Matheron go to: matheron@ag.arizona.edu.

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.