Potential use of insecticides and mineral oils for the control of transmission of major aphid-transmitted potato viruses

Abstract

Viruses occurring in Serbia and other countries in the region are a huge problem constraining seed potato production. At lower altitudes, in lowland and hilly regions, where table potato production is widely distributed, more than 50% of healthy plants become infected with potato virus Y during one growing season. Under these conditions, seed potato production is hindered due to a high infection pressure of potato virus Y which spreads far more rapidly compared to leaf roll virus, virus S and other viruses hosted by this plant species. This study tended to clarify a frequent dilemma regarding the use of insecticides in preventing the infection of healthy plants with potato virus Y and leaf roll virus, given the oral and written recommendations from pesticide manufacturers, agronomists and scientists in the field of crop protection arising from a logical conclusion that aphid vector control results in virus transmission control. The present findings, which are in agreement with reports of authors from other countries, show that the use of insecticides is ineffective in preventing potato virus Y which is nonpersistently transmitted by aphids from an external source of infection. However, insecticides can exhibit efficacy in preventing potato virus Y transmission from infected plants to healthy plants within a crop, which can have an overall positive effect only if seed potato is grown in areas that have no external source of infection. The present results and those of other authors show that insecticides are effective in preventing the infection of healthy plants with persistently transmitted leaf roll virus. Mineral oils provide effective control of potato virus Y by preventing the infection of potato plants with the virus. They can be combined with other management practices to protect seed potato crops against the virus. Given the fact that the initial first-year infection of healthy potato plants with virus Y in relation to leaf roll virus is approximately 10-20:1 under conditions in Serbia, and that the use of insecticides fails to ensure protection against PVY, this practice cannot have any positive effect on virus control under high infection pressure conditions.Virusi u Srbiji i drzavama regiona predstavljaju veliki problem i ogranicavajuci cinilac u proizvodnji semenskog krompira. Na nizim nadmorskim visinama, u ravnicarskim i brdskim podrucjima, gde je rasirena proizvodnja konzumnog krompira, Y virusom se zarazi u toku jedne vegetacije vise od 50% zdravih biljaka. U takvim uslovima nije moguca proizvodnja semenskog krompira zbog visokog infekcijskog pritiska Y virusom krompira koji se znatno brze siri u odnosu na virus uvijenosti lisca, S virus krompira i druge viruse ciji je ova biljka domacin. U ovom radu smo pokusali razjasniti dilemu, koja se cesto namece, da li ima efekta primena insekticida u cilju sprecavanja zaraze zdravih biljaka Y i virusom uvijenosti lisca krompira s obzirom na usmene i pisane preporuke, proizvodjaca pesticida, agronoma i naucnih radnika iz oblasti zastite bilja, koje nastaju kao posledica logickog zakljucivanja da suzbijanjem vektora, biljnih vasi, suzbijamo i prenosenje virusa. Rezultati nasih istrazivanja, sto je u saglasnosti i sa rezultatima istrazivaca iz drugih zemalja, pokazuju da primena insekticida nema efekta na sprecavanje prenosenja Y virusa, koji se vasima prenosi na neperzistentan nacin, sa spoljnog izvora zaraze. Medjutim, primena insekticida moze imati efekta u sprecavanju prenosenja Y-VKr sa zarazenih na zdrave biljke unutar useva krompira, a to moze imati ukupan pozitivni efekat samo ako se semenski krompir uzgaja u podrucjima bez spoljnog izvora zaraze. Nasi, i rezultati drugih istrazivaca pokazuju da primena insekticida radi sprecavanja zaraze zdravih biljaka virusom uvijenosti lisca koji se prenosi na perzistentan nacin ima efekta. U zastiti biljaka krompira od infekcije Y-VKr su efikasna mineralna ulja koja sprecavaju infekciju biljaka ovim virusom i koja se mogu koristiti sa drugim merama u sistemu zastite semenskog useva krompira od ovog virusa. S obzirom na cinjenicu da je, u nasim uslovima, pocetna jednogodisnja zaraza zdravih biljaka krompira Y virusom u odnosu na virus uvijenosti lisca priblizno 10-20:1, a primena insekticida ne osigurava zastitu od Y-VKr, onda ova mera ne moze imati nikakvog pozitivnog efekta u suzbijanju virusa u uslovima visokog infekcijskog pritiska. PR Projekat Ministarstva nauke Republike Srbije, br. TR31043: Research into plant pathogens, arthropods, weeds and pesticides towards the development of biorational crop management methods and safe food production