Cover crops, mulch lower night temperatures in citrus

Abstract

Winter often brings cold temperatures that can damage fruit or foliage in the San Joaquin Valley, posing an economic threat to citrus producers. Our experiments show that cover crops or mulch can lower minimum nighttime temperatures 0.90F to 2.20F in orchards, increasing the threat of freeze (frost) damage. Wind machines are typically used to protect commercial acreage from frost by mixing warmer air aloft with colder air near the surface, thus maintaining warmer minimum temperatures within the orchard. In locations where wind machines are not cost effective, management of the orchard floor is even more important. By using temperature forecast models that adjust for cover crops and mulches, growers can use wind machines more efficiently. Regardless, the decision to use cover crops must take into account all of their cultural benefits and drawbacks.