In vitro and postharvest assessment of fungicides in controlling anthracnose and stem-end rot of papaya fruits.
Liberato, J. R. and Tatagiba, J. S.
Summa Phytopathologica. Volume 27, Number 4, 2001. Pages 409-414.
2001
บทคัดย่อ
Anthracnose (caused by Colletotrichum gloeosporioides [Glomerella cingulata]) and stem-end rot (caused by many fungal species, mainly C. gloeosporioides and Phoma caricae-papayae) are the most important postharvest diseases of pawpaw in Brazil. In a study, the effect of different fungicides, applied at 100 mg a.i./litre concentrations, on the mycelial growth of C. gloeosporioides on potato dextrose agar was evaluated after incubation for 7 days at 26 deg C. Benomyl, captan, carbendazim, chlorothalonil, copper oxychloride, mancozeb, iprodione and thiophanate-methyl were not effective in inhibiting the mycelial growth of C. gloeosporioides. Other fungicides inhibited mycelial growth from 61 to 100% and these were tested at 1, 10, 60 and 100 mg a.i./litre concentrations. The DE50 and DE90 values (in mg/litre) obtained were: diniconazole (1.4 and >100), fenarimol (5.1 and 46.7), prochloraz (<1 and <1), propiconazole (< and 6.6), tebuconazole (<1 and 8.1), thiabendazole (48.0 and 85.9), triadimefon (9.3 and >100), triadimenol (8.9 and 54.4) and triforine (55.5 and >100). The effectiveness of benzimidazoles (benomyl, thiophanate-methyl, thiabendazole and carbendazim) and DMIs (triadimenol, tebuconazole, propiconazole and prochloraz) in controlling anthracnose and stem-end rot was evaluated in 3 postharvest trials under laboratory conditions. Twenty pawpaw fruits were dipped in a suspension of each fungicide at 1000 mg a.i./litre concentrations for 5 minutes. The intensity of anthracnose and stem-end rot were evaluated at 8-12 days following the fungicide treatments. The benzimidazoles were not effective in controlling both diseases. Triadimenol showed high effectiveness in the control of stem-end rot. Other DMIs showed 100% control of both diseases, but showed phytotoxicity to pawpaws. In a fourth postharvest trial, 20 fruits were dipped in prochloraz suspensions at 100, 250, 400, 500 or 1000 mg a.i./litre for 5 minutes. Prochloraz at 400 mg a.i./litre resulted in 100% control of both postharvest diseases, while the same fungicide at 250 mg a.i./litre resulted in 95% of both diseases. However, phytotoxicity symptoms were induced as these concentrations. Prochloraz at 100 mg a.i./litre showed no phytotoxicity and gave 66 and 85% control of anthracnose and stem-end rot, respectively.