Possible induction of potato plant defences against Potato virus Y by mineral oil application

The virus disease occurring in the potato varieties Harbinger, Aquila, and King George V was probably the potato rugose caused by potato virus Y (Solanum virus 2). In the variety Harbinger, the degree of strength of the virus disease probably varied as a result of the appearance of different races of potato virus Y. The type of the virus disease did not change from one vegetative generation of the potato to another. In the potato varieties Aquila and King George V, only the severe type of the disease was observed. The severe type of the virus disease reduced the tuber yield of all the potato varieties investigated to a level of 5 to 6 %, and the slight type occurring in the variety Harbinger to an average of 27 % of the normal. The virus infection appeared more frequently in Harbinger than in the variety Aquila. In the summer, when the infection of the potato plant took place, the virus disease reduced its productivity only relatively little. In the following vegetative generation of the diseased potato plants, the degree of their degeneration conclusively displayed itself. Following this, the wakening of the virus diseased plants did not progress further from one vegetative generation to the next.

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Comparison of mineral oil, insecticidal and biopesticide spraying regimes for reducing spread of three potato virus Y (PVY) strains in potato crops

Plant Disease ◽

10.1094/pdis-06-21-1213-re ◽

2021 ◽

Author(s):

Tyler Donald MacKenzie ◽

Xianzhou Nie ◽

Mathuresh Singh

Keyword(s):

Potato Virus ◽

Potato Virus Y ◽

Field Experiments ◽

Residue Analysis ◽

Foliar Spray ◽

Mineral Oil ◽

Organic Production ◽

Chemical Insecticide ◽

Hypersensitive Resistance ◽

Resistance Response

In-field management of potato virus Y (PVY) faces challenges by changing availability and environmental acceptability of chemical agents to control aphid vectors of the virus, and by proliferation of PVY strains with different symptomology and rates of spread. Over 2018-2020, foliar spray treatments were compared in field experiments in New Brunswick, Canada, to measure effectiveness at reducing spread of PVYO, PVYN:O and PVYNTN strains. Mineral oil, insecticide, combined oil and insecticide spray and a biopesticide (i.e., LifeGard® WG) were compared. Insecticide-only and mineral oil-only were not effective, though several combined oil and insecticide, and biopesticide treatments significantly reduced PVY spread. The biopesticide was proportionately more effective with recombinant PVYN:O and PVYNTN strains, possibly from exciting the plant’s hypersensitive resistance response only caused naturally in cv. Goldrush by PVYO. Pesticide residue analysis showed that mineral oil enhanced the retention of pyrethroid insecticide in the potato foliage longer than with insecticide applied alone, which may explain the beneficial synergistic effect of combined sprays for reducing PVY spread. Tuber yields were generally unchanged in chemical insecticide treatments but were slightly lower in biopesticide treatment. The cost per PVY protection was competitive across all effective treatments, including biopesticide, however, there was some revenue loss from lower yield with the biopesticide. This biopesticide is organic-certified, however, thus a small premium on price for organic production could offset this yield deficit.

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