Clarissa Reyes, North Sacramento Valley Orchard System Staff Research Associate
Please note that the following are general recommendations intended to help you keep track of regular practices in a busy time; the optimal timing for management practices may vary based on specific location and conditions.
- Irrigation: Irrigate to maintain mild to moderate water stress post-harvest. Stem water potential should be between -12 and -16 bars as measured by a pressure chamber. Avoid high water stress levels as Cytospora spreads faster in stressed trees compared to adequately watered trees.
- Salinity: Take soil samples to check soil salinity and toxic salt (chloride, sodium and/or boron) levels going into what could be a dry winter. This is especially important for newer orchards on Krymsk 86 rootstock, which is more sensitive to chloride than Marianna or Myro. UC ANR provides a free video series on soil sampling.
- Zinc: Apply foliar zinc (Zn) to correct zinc deficiency (July leaf sample <18ppm). Spraying 20 lbs/acre of 36% zinc sulfate as natural leaf drop begins in late October can deliver needed zinc into the tree and, in addition, can facilitate leaf drop, reducing risk of blow over and/or disrupting aphid reproduction.
- Cytospora: Prune to remove Cytospora and to manage next year’s crop.
- Remove existing cytospora cankers and spore sources by cutting branches several inches to a foot below the symptoms and burn prunings (if permitted).
- Consider your management goals: topping young vigorous trees before a big wind can reduce risk of blow-over, while long pruning can increase early yields in young prune plantings.
- Prune early in the fall to allow cuts to harden off before seasonal rains. Protect fresh wounds from water-borne spores with a fungicide spray (Topsin-M® or Topsin-M® + Rally®).
- Orchard Sanitation: Sanitize your orchard by removing fruit mummies and blighted shoots to remove disease inoculum. Remove bark damaged during harvest, and backhoe out diseased or dead trees to prepare for replants.