THE POTATO MOTH.

Marlborough Express, Volume XLVII, Issue 25, 30 January 1913, Page 6

THE POTATO MOTH.

A TROUBLESOME PEST

A paper on "The Intensity of the Life jFonsia of the Potato Moth" was contributed to the Australian Science Confess- by Dr- Steward. The potato moth, he said, was probably one of the- most troublesome pests which ravage the potato crops of the Commonwealth. Protective methods comprised the steeping of tubers in solutions of formalin, mercuric (.♦blonde, etc., treatment with lime and other substances, and fumigation with carbon. Experiments showed tihat wken larvae-infested tubers were steeped in solutions of formalin piepared by mixing £, 1, or 2 pints of the coß'.pound with. 15 .gallons of crater, it required a steep of 24 to 4A hoars' duration to ensure the destruction of the invading larvfe. Oontrol experiments, in which the! infected material was steeped in water alone and for similar periods, indicated- that this method of ■ treatment was quite as effective as the! sleeping in solutions of formalin. During the earlier stages drowning rather than poisoning of the infesting invvss took place. Similarly conducted experiments with isolated i Inrvse show that these organisms were { wall, able to- withstand a steep of i i i<» 6 hours' duration in solutions of j tormalia, of half to 2 hours' duration in a of mercuric chloride ilctz. to S gallons of water). Similar i^ults attended the steeping of larvae in an aqueous 1* per cent, solution of copper sulphate; a steep of 6 hours' duration fails to., seal the fat* of the larva?. When egg-infostod Lubors are immersed for a p-ariod of < 12 hours in a solution of mercuric ■ h]nr-"rlpi Hot;, to 8-.gallons of water), - t

the treatment was quite ineffective. Steeping in aqueous solutions of 5 per cent, or 10 per cent, sulphuric acid for 1 to 2 hours yielded similar results. Experimental work directed to the aim of ascertaining whether the steeping of uninfested tubers in a solution of mercuric chloride or in suspension of lead-arsenate would prove effective against infestation •showed that their means of treatment was quite ineffective. In regard to the treatment of tubers by steeping, the period of fumigation was restricted to 48 hours, and the amount of fumigation to lib. to 21b. per 1000 cubic feet; then initially unsprouted tubei-s might be intermittently fumigated 2, 3, and possibly 4 times without endangering the vitality of the tuber buds. Tubers subjected to intermittent fumigation and a subsequent storage period of two to three months, on planting had yielded quite as good crop results as similar but unfumigated tubers.