Almonds and Stonefruits
Project Leaders: Greg Browne, USDA-ARS, Dept. of Plant Pathology UC Davis, firstname.lastname@example.org; Bruce Lampinen, Dept. of Plant Sciences, UC Davis; Shrini Upadhyaya, Dept. of Biological and Agricultural Engineering, UC Davis
The problem addressed by this project was the need for stable alternatives to pre-plant soil fumigation with methyl bromide (MB) to control replant problems in the almond and stone fruit industries of California.
Growth and productivity of replanted orchards are often suppressed by“replant problems” unless precautions are taken. Replant problems can result from interacting physical, chemical, and biological factors (Fig. 2). The development of a young replanted orchard can be severely compromised by suboptimal physical or chemical soil properties. Young root systems and their scions are especially “sensitive” to soil compaction, salt accumulation, nutritional deficiencies and chemical toxicities, all of which can occur when one crop is planted after another. Probably the most widespread of biological replant problems is replant disease, a poorly understood soilborne complex that suppresses growth and cumulative yields in successive plantings of almond and other stone fruit orchards (Browne et al., 2006; Bent et al., 2009.)
Although they tend to be site specific and localized, aggressive pathogens and pests such as Phytophthora species, Armillaria mellea, and Verticillium dahliae and the ten-lined June beetle can cause severe damage in young orchards as well as older ones, although losses caused by these pathogens tend to be localized and sporadic (Larsen, 1995; Strand, 1999, 2001.)