Through the use of a dye solution, evidence was obtained that a liquid disinfectant may be forced into the narcissus bulb parts invaded by nematodes and fly larvae by immersion in vacuo.An investigation of the lethal properties of solutions against nematodes and their influence upon bulb growth led to the selection of a silver nitrate solution as a promising disinfectant, but owing to instability of silver nitrate in the presence of chlorides and other substances in tap water and in dirt clinging to bulbs, its use had no commercial possibilities. However when silver salt was combined with potassium cyanide in the ratio of 1 to 3 by weight, an effective solution of satisfactory stability was obtained.A solution of silver nitrate 0.05% and potassium cyanide 0.15% by weight, forced into narcissus bulbs by an evacuation process, effectively destroyed bulb nematodes and bulb fly larvae without significant injury to bulb growth under greenhouse conditions.Field tests with bulbs treated in silver nitrate-potassium cyanide solutions resulted in the reduction of infection from 26.8 to 1%, a 96% control, and no evidence of injury in the foliage or bloom was detected.
Culture filtrates of five species of Altermaria were antagonistic $0 PkytoQhtko~a eryLkroseptica. Those of A. rcedkz'nu exerted the greatest effect and they were foliou~ed in order of effectiveness by A. diantkico%a, A. sodaazi, A. brassa'cicoia, and A. ienuis, The antagonistic principle in the filtrate of A, radicina was readily removed by activated carbon. By extracting this carbon with acetone, substantial yields were obtained of colorless, needlelike crystals, quite in~soluble in water, but readily soluble in acetone, ethyl alcohol, ether, benzene, cotrcentrated strlphuric acid, and 10yo ssocliarrza hydroxide. 'The m.p. of the cryetals, 204°C. t o 208DC., and the deep pink color in solutions of sodium hydroxide distinguish the substance from alternaric acid.Water suspensions of the crystals were much less antagonistic t o P. euythroseptica than the original filtrate and had little or no effect upon several species of bacteria.8. BRIAN, p. Iv., CURTIS, 9. J.
Freshly cut sections of frozen potato tuber and apple fruit tissue exhibit a brilliant fluorescence when examined in a dark room under an ultra-violet (Stroblite) lamp. The fluorescence disappears from the apple tissue upon thawing but is retained in potato tuber tissue. Thus the ultra-violet lamp serves as a useful diagnostic means of detecting frost or low temperature injury in potato tubers. Many other plant tissues were frozen and examined, but proved to be non-fluorescent. Acetone extracts of both normal and frozen potato tuber tissue were fluorescent, but similar extracts of both frozen and normal apple fruit were not. Although normal potato tissue is non-fluorescent and frozen tissue is brightly fluorescent, no differences were found in the brightness of the acetone extracts.
In a moist environment, a minimum exposure of 120 min. at 110–113°F. is required to destroy pre-adult larvae of the bulb nematode Anguillulina dipsaci (Kühn, 1858) Gerv. and v. Ben., 1859, but progressively shorter exposures are required as the temperature is raised. At 116.5–118.5°F. the lethal exposure is 60 min. and at 118.5–120°F. an exposure of 30 min. is required.In a dry environment exposures of 150 min. to temperatures as high as 140°F. are not lethal to pre-adults and the heat treatment does not affect their ability to induce the characteristic symptoms of infestation in barley seedlings.The pre-adults are more resistant to heat than any other stage in the life history of the nematode.The data suggest that the ineffectiveness of the standard hot water treatment when applied late in the season is due to the fact that the major development of pre-adults takes place after the bulbs are lifted, and also because the masses of dormant pre-adults are often well isolated from the moisture of the bath by the bulb scales and corky basal plates, and are more resistant to heat in a dry, compared with a moist, state. It is recommended that the hot water treatment be employed not later than four weeks after lifting when the lifting is done as soon as the foliage dies down.A pre-soak is suggested as a possible means of increasing the effectiveness of the standard hot water treatment.
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