Preharvest sprays of fungicides to control gray mold by Botrytis cinerea in postharvest pear fruit in Argentina

SOSA, M.C.; ELDESTEIN, R.; MANTEGNA, M.; LUTZ, M.C.

Santa Cruz

Simposio; XVII INTERNATIONAL BOTRYTIS SYMPOSIUM; 2016

Botrytis cinerea is one of the main postharvest pathogens, mainlyaffecting Beurre Bosc and Beurre D ́Anjou pear fruit cultivars in thePatagonian orchards, Argentina. Decays by B. cinerea become from field latentfruits infections of calyxes and stems, or by wounds at harvest or post -harvest.Decays develop during the ripening of the fruit, causing significant economiclosses. Due to the presence of latent infections, we propose to assess the useof new non register fungicides on pear fruit on the B. cinerea decay control.Sprays with fungicides were conducted in orchard of Beurre Bosc cultivar duringthe 2012/13 and 2013/14 growing season. In 2012/13, we studied the effect ofpyraclostrobin (pyr) 12.8% w/w + boscalid (bos) 25.2% w/w, 50g·HL-1 andmyclobutanil (mycl) 40% w/w 15g·HL-1 (registered for powdery mildewand scab), 30 days before harvest (DBH). In 2013/14, we evaluated pyr+bos andessential oils from Melaleuca alternifolia 0.06L·HL-1, 7 DBH. Inboth seasons, water was a control treatment. Fruit was harvested and storage at-1/0°C, and 98%RH. The incidence percentage (%I) of gray mold was evaluated onartificially wounded and unwounded fruits, in each preharvest treatment. In2012/13, we observed that fungicides applied at preharvest significantlyreduced the incidence of decays by B. cinerea at postharvest, after 120d of coldstorage. The fruit treated with water (without fungicide) had 6 %I, while thefruit treated with pyr+bos and mycl had 0.3 %I (95% DR) and 1.55 %I (74% DR),respectively. In the wounded fruit at harvest, we observed 10.5 %I, whereasonly 1 %I (92.7% DR) with pyr+bos and 1.5 %I (83 DR) with mycl. We alsoevaluated the effect of preharvest treatment plus a fludioxonil (flu) 23 % w/vspray at postharvest. After 120 days, these treatments diminished on about 100%the decay incidence respect to the effect of flu alone. During 2013/14, after100 days of cold storage, unwounded fruit had low incidence (1%I) of B. cinereaand it was not observed differences between treatments. However, pyr+bos andoils of M. alternifolia reduced the decays by Alternaria in about 30 and 48 %,respectively. In relation to wounded fruits, was demonstrated the effect ondecays, diminished from 10%I on the water alone treatment to 5 and 2.3% withthe fungicide treated fruits. These promissory results become as the firstcontribution about the use of new fungicide in preharvest in order to reducethe pear fruit postharvest decay in Argentina.