Protects potatoes against rots

Press, 1 May 1981, Page 17

Protects potatoes against rots

The application of thiabendazole (Tecto Flowable) as a tuber protectant against the storage rots gangrene (Phoma exigua var. foveata) and dry rot (Fusarium solani var. coeraleum) has been made easier for some growers by mounting the spray application unit on the harvester.

Potato storage rot diseases, particularly gangrene, have caused growers considerable problems over the past two seasons. The brown to black surface depressions (often likened to thumb marks) with diseased tissue extending deep into the tuber can appear at any time from shortly after harvest to the end of the storage period. Serious losses can result when potato lines are heavily infected.

The application of a fine spray-mist of thiabendazole has been shown to give good

The accompanying item on protecting potatoes against rots using a spraying unit mounted on the harvester has been contributed by Dr J. Hedley, officer-in-charge of the Ministry of Agriculture’s plant health diagnosticstation at Lincoln.

control of the disease if applied within a fortnight of harvesting. This operation has been carried out as tubers are passed over a grader or when moving up an elevator into a bulk store. The location of the treatment unit on the grader or elevator does not suit all growers’ operations; some growers prefer to grade later in the season.

With this in mind, a system by which the treatment can be applied on the harvester so all tubers are protected from the storage rot diseases mentioned earlier

has been developed (in line with that used elsewhere). The photograph shows the system developed by Mr Graeme Blackburn, of Alex McDonald (Merchants), Ltd, and Linton Engineering Co., West Melton.

The spray unit is mounted on this Grimme single row harvester at the end of the inspection table. Two nozzles (see arrows) direct a fine mist of thiabendazole onto the tubers as they reach the end of the table. There is normally another shield on the near side of the nozzles opposite the one shown in the photograph. The shields stop the mist application being affected by wind and being blown away from tubers (and onto the tuber inspectors). The pump is operated from the harvester's main shaft. The whole unit is now being produced in bolt-on kit-set form.