CONTROL OF BROWN ROT AND BLUE MOLD OF SWEET CHERRY FRUIT WITH COMBINATIONS OF PRE-HARVEST IPRODIONE, POST-HARVEST CRYPTOCOCCUS INFIRMO-MINIATUS, AND MODIFIED ATMOSPHERE PACKAGING
RA SPOTTS1, LA CERVANTES1, T FACTEAU1 and T CHAND-GOYAL2
1Mid-Columbia Agricultural Research and Extension Center, Oregon State University, Hood River 97031, USA; 2Department of Plant Pathology, University of California, Riverside 92507, USA
Background and objectives
The cherry industry is interested in reduction of decay by nonchemical means and maintenance of fruit quality during long term storage and distant transport. To achieve these goals, the effectiveness of preharvest iprodione and postharvest C. infirmo-miniatus treatments alone and in combination for control of decay of sweet cherry fruit was studied. The effect of a modified atmosphere on brown rot control was evaluated as a part of the ipodione-C. infirmo-miniatus combinations.
Materials and methods
lprodione was applied at the rate of 0.44 kg/ha to sweet cherry trees cv. Lambert in 1996 and 1997. The postharvest treatment suspensions in which cherry fruits were dipped included M. fructicola aione (control) and C. infirmo-miniatus plus M. fructicoia. The concentrations of M. fructicoia and C. infirmo-miniatus were 1 x 104 conidia/ml and 0.51.5 x 108 cfu/ml, respectively. These treatments were applied to fruit in each of the three preharvest regimes (no spray and iprodione at 5 and 14 days PHI) in 1996 and in the two regimes (no spray and iprodione at 7 days PHI) in 1997. Treated fruit were stored in air at 2.80C for 20 days in both years and in modified atmosphere packaging (MAP) at 11.5% carbon dioxide and 5.1% oxygen at -0.50Cfor42 days in 1997 before disease evaluation.
Results and conclusions
In 1996, all treatments reduced blue mold and all except C. infirmo-miniatus alone reduced brown rot. Iprodione applied 5 days PHI combined with C. infirmo-miniatus was better than the 14 day PHI iprodione alone (blue mold and brown rot) and the 5 day PHI iprodione alone (brown rot). In 1997, for air-stored fruit, iprodione and the combination of preharvest iprodione with postharvest C. infirmo-miniatus reduced brown rot incidence, but C. infiffno-miniatus alone had no effect when compared with the control. MAP alone significantly reduced the incidence of brown rot of sweet cherry fruit when compared with air alone. For MAP-stored fruit, either the iprodione or the C. infirmo-miniatus treatments alone significantly reduced brown rot incidence. The combination of the iprodione and C. infirmo-miniatus was more effective than iprodione alone. The iprodione-C. infirmo-miniatus synergism may be the result of low fungicide residue slowing germination and growth of M. fructicola which would give the iprodione-resistant C. infirrnominiatus time to colonize the fruit surface and wound sites and compete for nutrients . The C. infirmo-miniatus-MAP synergism for control of brown rot may be related to a combination of suppression of M. fructicola  and stimulation of C. infirmo-miniatus by the high carbon dioxide. Implementation of the preharvest iprodione-postharvest C. infirmo-miniatus-MAP system would increase decay control during long-term storage and transport of sweet cherry fruit and decrease fungicide usage.
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