Potato Variety Tolerance to Herbicides, Weed Interaction with Insects and Virus, and Trap Crop Management in Potato Cropping Systems
Potato growers use integrated weed management tools including timely cultivation, herbicides, and crop rotation. University of Idaho research has shown that cultivation can cause potato tuber yield and quality losses. Potato yields could decline by 32% without herbicides. An estimated 90% of Idaho acreage is infested by nightshade sp. There are four main herbicides labeled which can provide nightshade control, however, these herbicides have caused potato crop injury, tuber yield and quality losses. Since potato is a minor crop, many crop protection manufacturers consider the potato market too small to invest development dollars and will not likely develop new potato-specific herbicides in the near future or expand potato herbicide labels with additional application timings. The Tri-State Breeding Program traditionally conduct metribuzin
tolerance trials with not-yet-released cultivars. However, these and recently released varieties are not generally tested for tolerance to other, newer potato herbicides such as dimethenamid-p, flumioxazin, or fomesafen. The specialty variety market is growing so there is a definite need for information about variety tolerance to these herbicides. Hairy nightshade has been shown to serve as a significant alternate host to major potato diseases such as Potato Virus Y and Potato Leafroll Virus as well as being the preferred host for green peach aphid - the principal PVY and PLRV vector and also serve as a bridge for late blight and some nematodes that are devastating to potatoes, during the crop rotation years when potatoes are not present in a field. The potato industry has identified PVY as one of its most serious disease problems and is looking for ways to reduce overall disease
incidence below an economic threshold and to eliminate the new tuber necrotic isolates that pose a serious threat to the seed and commercial industries. Need for a comprehensive, multidisciplinary, integrated virus-vector-alternate/weed host management plan was strongly expressed by all in attendance. Until 2006, the United States was thought to be Potato Cyst Nematode free. However, PCN has recently been found in southeastern Idaho (2006). PCN eggs hatch in the presence of a host triggered by exudates from the host roots. The threat of PCN in Idaho is that seed potatoes from PCN-infested fields may not be sold to Canada, and trade with other countries also is impacted. Quarantines would affect the potato industry as well as any agricultural commodity shipped from the regulated areas and carrying soil (e.g. all nursery, turf, root, and tuber crops) in the regulated areas. Several
eradication strategies are being evaluated as tools to aide in the eradication effort including use of trap crops. Solanum sisymbriifolium is a trap crop being researched and sold in Europe to remove PCN from infested soils. The plant does not allow the nematodes to complete their life cycle and reproduce. Since S. sisymbriifolium can become a noxious weed in warmer climates, introduction of it as a trap crop should be tempered with research to determine how to control weedy volunteers of the crop in an overall management scheme for use.