2012 Annual Report
1a.Objectives (from AD-416):
This collaboration will explore methods that have the potential to contribute to the effort to eradicate potato cyst nematode in Idaho and provide alternatives to the use of methyl bromide.
1b.Approach (from AD-416):
We will continue our efforts to identify individual hatching factors using LCMS and hatching assays by fractionation of concentrated extracts. Hatching efficacy of fractions will be evaluated at the Moscow lab at UI. We will determine whether crude root exudate can also be used to induce a suicide hatch and production systems to capable of producing large quantities of highly active hatching factors that could be deployed on a commercial scale. We will evaluate different germplasm to see if some genotypes are particularly rich sources of hatching factors. We will examine ways to increase the activity of root exudate. We will explore ways to increase the efficacy of potential trap crops, concentrating on S. sisymbriifolium, including way to increase its root mass to allow better control in infested fields (ie more root mass, deeper root growth) and confirm that any potential trap crop does not allow reproduction of the Idaho G. pallida population. In order to maximize production of biomass, root mass, and hatching factors in the soil, more must be learned about how to grow these plants for maximum effectiveness. We will evaluate different planting dates, seeding rates and weed control practices under greenhouse and field conditions in eastern Idaho in an attempt to optimize above and below ground biomass production. We also need to know how to kill the green manure and trap crops at the end of the season and manage the potential for these plants to spread and act as weeds. We will evaluate the potential of these crops to produce seed, and assess the most effective ways to control volunteers in succeeding crops.
This team has been exploring numerous research objectives that are relevant to eradicating the Idaho population of PCN, addressed in sub-objective 1.B. of the related in-house project, "Develop germplasm with resistance to pests and diseases, establishing effective and efficient screening protocols, determining range of expression, inheritance, heritability, and discover molecular markers, while mapping genetic factors where possible and useful". We are examining possible biocontrol agents (BCA). The genus Plectosphaerella has frequently been isolated from nematode eggs and is a promising BCA. The species Paecilomyces lilacinus is currently being commercialized in Australia for use against cyst and root-knot nematodes. We have observed reduced viability of PCN in preliminary growth chamber experiments using conidial suspensions of P. lilacinus, P. cucumerina, and Fusarium sp. (Worapong & Dandurand, unpublished). We are also working on methods to measure the growth and proliferation of the BCAs in soil and monitor their interactions with cysts and juveniles, including the use of qPCR.
Numerous weeds found in the Northwest have been analyzed to determine whether PCN can reproduce on them, so that any such weeds can be eliminated from areas at risk. We have identified hairy nightshade (Solanum sarrachoides) (both Washington and Idaho biotypes) and cutleaf nightshade (S. triflorum) (only Idaho biotype) as hosts of the PCN pathotype from Idaho. A cutleaf nightshade biotype from Washington and black nightshade (S. nigrum) were not suitable PCN hosts in preliminary studies.
We identified sticky nightshade as a potential trap crop that can be used in the PCN eradication effort. Moreover, we produced a naturally genetically modified plant that had greater root growth in the greenhouse than the wild type plants. Both of these types of sticky nightshade types are currently undergoing field trials in Parma, Idaho, to define the agronomic factors that will influence the effectiveness of the trap crop. Sticky nightshade was planted at two different locations in Idaho and germination parameters identified to establish the seeding density needed. The crop is being closely monitored to determine the optimal ways to mitigate its weed potential.