Preharvest Practices to Minimize Postharvest Decay
- Use low angle nozzles to keep irrigated water
off fruit on lower limbs to reduce sprinkler rot
(Phytophthora cactorum). Maintain 1 ppm copper in the
- Maintain good weed control and keep grass
mowed. A drier orchard microclimate will reduce mucor rot,
coprinus rot and scab.
- Control woolly aphids to reduce bull's eye
- Supplement fruit calcium with foliar calcium
sprays during the growing season. High calcium fruit is
less prone to decay and physiological disorders than low
- Use the minimum amount of nitrogen fertilizer
necessary to maintain plant vigor. High N fruit is more
prone to various postharvest problems than lower N fruit.
Application of N immediately postharvest may minimize fruit
N while still supplying enough for fruit set and shoot
growth the following year.
- Do not use Benlate or other benzimidazole
fungicides in the orchard to avoid development of
resistance in the packinghouse. Resistance to Benlate will
reduce the effectiveness of other postharvest fungicides
including Mertect 340-F and Deccosalt 19.
- Early season and preharvest applications of
Ziram to orchards susceptible to bull's eye rot, side rot
and pear scab infections will help reduce postharvest
decay. Follow application instructions in EB0419, Crop
Protection Guide for Tree Fruits in Washington.
- Harvest at proper maturity. Late-picked fruit
is more susceptible to decay than fruit of optimum
- Clean bins thoroughly before filling with
fruit. Steam is very effective. Remove last season's leaves
and fruit parts prior to placing bins in the orchard. Decay
spores survive on the wood of bins, especially where fruit
has been smashed. Apple and pear scab-infected leaves
survive through storage. Growers in districts without scab
are advised to use only bins free of scab-infested leaves
to avoid new infections.
- Reduce bin contact with dust and dirt, which
contain spores of decay fungi. Keep the bottom of bins as
clean as possible. Keep staging areas mowed. Suppress
- Avoid picking fruit when it is wet.
- Keep grounders (fallen fruit) out of bins.
- Do not allow bins of fruit to remain in the
sun. Transfer fruit quickly to the packinghouse and cold
- Handle fruit gently. Avoid bruising and stem
punctures. Smooth orchard roads and driving forklifts
slowly may reduce fruit injury.
- After harvest, remove fallen fruit from orchard
to prevent buildup of decay spores.
- Apply copper at leaf-fall to help reduce bull's eye rot.
Dr. Eugene Kupferman, Postharvest Specialist
WSU Tree Fruit Research and Extension Center
1100 N. Western Ave., Wenatchee, WA 98801
Tree Fruit Postharvest Journal 4(1):7