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.
3. Progress Report:
This project contributes to in-house project Objective 1: "Identify superior germplasm for potato disease and pest resistance, phytonutrients, minerals and vitamins, using high-throughput methods to determine the extent of natural variation in diverse potato germplasm of select phytonutrients/metabolites. These traits will be incorporated into the cultivated breeding pool using traditional breeding and molecular approaches"; and Objective 2: "Determine host resistance options, epidemiological parameters and develop diagnostic tests for emerging pests and pathogens of potato". Trap crops are non-host crops that stimulate PCN egg hatching but do not support nematode reproduction. They are a promising option to control PCN, because hatched juveniles have limited food reserves and will die if they do not successfully parasitize plant roots within days. One promising trap crop is S. sisymbriifolium (SS). We found that its roots can access greater depths of the soil than fumigants without the environmental consequences. In preliminary greenhouse experiments a complete elimination of PCN reproduction was observed using SS versus potato. A study of the life history of G. pallida on SS found landmark changes in the appearance of either the nematode or its infected host. By week 4 post-infection, many fewer J2s are found in litchi tomato roots compared to potato, and their development was arrested. Preliminary evidence suggests a new potential trap crop candidate may have been identified. Work is ongoing to extend and repeat these findings. The new putative trap crop is not typically grown in the Pacific Northwest, so a field trial is underway in Parma, Idaho, to evaluate the agronomic performance of the candidate crop. Finally, greenhouse experiments were established to evaluate potential biocontrol agents (P. cucumerina and T. harzianum), on viability and hatching of PCN under different cropping systems. Results indicate a reduction in viability when soil was infested with the biological control agents.