ISHS Acta Horticulturae 619: XXVI International Horticultural Congress: Potatoes, Healthy Food for Humanity: International Developments in Breeding, Production, Protection and Utilization
THIDIAZURON, A CYTOKININ-LIKE COMPOUND, ENHANCES FUNGICIDAL ACTIVITY AGAINST EARLY BLIGHT IN POTATO |
| Author: | A.D. Pavlista |
| Keywords: | TDZ, Dropp, EBDC, mancozeb, chlorothalonil, Solanum tuberosum, ‘Russet Norkotah’, ‘Atlantic’, Alternaria solani, leaf necrosis, anti-senescence |
| Abstract:
Early blight (caused by Alternaria solani) is an important disease of potato and is associated with leaf senescence and stress. Thidiazuron (TDZ), a growth regulator, exhibits cytokinin-like activity including anti-senescence. Would TDZ alone or added to common protectant fungicides delay the onset and progress of early blight? In 1992, 1994 and 1995, TDZ alone was tested at 140, 280 and 560 g/ha on the potato (Solanum tuberosum) cv. Russet Norkotah, and compared to mancozeb (MNZ) at 1.68 kg/ha. In 2001, TDZ at 560 g/ha, MNZ with and without TDZ, and chlorothalonil-zinc (CHZ) with and without TDZ, were compared on cv Atlantic. Plots were evaluated every few days after treatment by percentage of plot exhibiting foliar necrosis. Disease progress curves were compared to evaluate the time for plots to reach 25, 50 and 75% leaf necrosis, and areas under the disease progress curves (AUDPC) were calculated. TDZ delayed the progress of leaf necrosis by early blight by two and five days on ‘Russet Norkotah’ and ‘Atlantic,’ respectively. MNZ delayed necrosis five to six days on both cultivars, and CHZ delayed it eight days on ‘Atlantic.’ When TDZ was added to MNZ and CHZ on ‘Atlantic’ in 2001, the delay in disease progress was extended to 10 and 11 days, respectively. TDZ gave an additional three to five days of protection against early blight. AUDPC calculations verify these delays in early blight progress because adding TDZ lowered the AUDPCs of MNZ and CHZ. TDZ with either fungicide decreased susceptibility, as indicated by the AUDPC, of plants to freeze damage which occurred prior to the 2001 trial’s conclusion. TDZ prolonged plant tolerance to the spread of early blight suggesting that maintaining healthy plants and delaying aging lessens their susceptibility to early blight leaf necrosis. | |
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