Age Considerations: Different irrigation strategies are required to ensure that both young and mature walnut orchards avoid fall frost and winter freeze injury

摘要

IT probably comes as no surprise to nut growers that walnuts can be damaged by both fall frosts and hard winter freezes. Problems certainly aren't encountered every year, but about every half-dozen years or so California's San Joaquin and Sacramento Valleys — where most of the nation's walnuts are grown — sustain temperatures cold enough to damage trees. It's to be expected, says University of California Cooperative Extension Farm Adviser Joe Grant, and growers need to make the necessary preparations. However, what some growers may not know is that young trees, from the first leaf, face different risks from the cold than mature orchards. The difference is due, of course, to the trees' physiology, but it is also a function of the increasing popularity of certain varieties, says Grant. "We've been planting late varieties such as Chandler and Howard, and more vigorous varieties like Tulare," says Grant, who's based in Stockton.