Plant-parasitic nematodes are economically important pests of agricultural crops produced in the North Central Region (NCR). Most notably, the NCR is the dominant region in the U.S. for corn, soybean and small grain production. In addition, the NCR is home to large production areas of several vegetable crops (e.g. sugar beets, cucurbits, potatoes). The presence of plant-parasitic nematodes in these production systems can cause substantial economic losses, in some cases exceeding $1 billion US. The long-term goal of this committee is to provide environmentally sustainable, effective and economic management of plant-parasitic nematode in the NCR.

The need as indicated by stakeholders

Access to unbiased data is the cornerstone for successful plant-parasitic nematode management by stakeholders (crop consultants, industry professionals, growers, breeders, Extension professionals, etc.). Plant-parasitic nematodes are some of the most economically damaging pests of agronomically produced crops in the midwestern United States. Heterodera glycines, the soybean cyst nematode (SCN), has been estimated to be the greatest yield-limiting pest of soybeans in the United States and Ontario for more than a decade (Wrather and Koenning 2006; Allen et al. 2017) responsible for an estimated 123 million bushels lost annually, or $1.2 billion in revenue lost each year, from 2010 – 2014. In addition, other nematodes (e.g. Rotylenchulus reniformis, Belonolaimus longicaudatus, and Meloidogyne, Helicotylenchus, Hoplolaimus, Paratrichodorus, and Pratylenchus spp.) account for an estimated 11 million bushels of soybeans lost each year over this same period.

In addition, plant-parasitic nematodes are considered to be among the top 10 most destructive diseases of corn in the United States and Ontario (Mueller et al. 2020). From 2016 – 2019, an estimated 270 million bushels of corn were lost as a result of plant-parasitic nematodes affecting corn production in the United States and Ontario. Nematodes included species belonging to the genera Belonolaimus, Helicotylenchus, Hoplolaimus, Longidorus, Meloidogyne, Paratrichodorus, Pratylenchus, Tylenchorhynchus, and Xiphinema. Many of these same nematodes also are known to be destructive to other field crops in the region including wheat and alfalfa as well as regionally important vegetable crops (Society of Nematologists Crop Loss Assessment Committee 1987; Koenning et al. 1999). In an effort to increase food security and information access, this project will address both applied and fundamental questions pertaining to yield loss attributed to plant-parasitic nematodes in all of the above mentioned economically important crops in the region.

The importance of this work and what the consequences are if it is not done

The NCR spans a large geographical region from north to south and east to west which makes for a wide diversity of nematode species throughout the region. This diversity of nematode species is also the result of soil edaphic factors, rotations, climatic conditions, and management methods. Yield losses due to plant-parasitic nematodes in many areas are often erroneously attributed to other causes such as nutrient deficiencies, poor soil quality, or other diseases. Lack of understanding of the impacts of plant-parasitic nematodes on crop production means less effective management, lost bushels and lost revenue.

One of the best examples of the impacts of nematodes on production is SCN. For more than 20 years, the PI 88788 source of resistance has been used to manage SCN in soybean varieties. Today, PI 88788 is present in approximately 95% of soybean varieties. The repeated use of this same source of resistance over an extended period of time has led the reduced effectiveness of the PI 88788 source of resistance on many field populations. In field trials in Iowa, by simply rotating to the Peking source of SCN resistance vs PI 88788, a grower can increase their profitability by as much as $200 per acre (Tylka 2020). More typically, a grower has the potential to increase yields by 15-20 bushels per acre by simply changing from a PI 88788 variety to a variety with the Peking source of SCN resistance.

Though awareness of plant-parasitic nematodes has increased slightly among stakeholders in recent years, this increase has largely been attributed to industry marketing of products for plant-parasitic nematode control. Our committee has provided access to unbiased data regarding many of these products. As new products are developed, it is essential that coordinated research spanning across state lines provides answers to these and other stakeholder questions. Meaningful data comparisons can only be extrapolated through such coordination and synchronization of experimental designs across multiple states in the NCR. This type of coordinated research allows for understanding of how environmental variability impacts nematode management, biology, and other factors which ultimately allows for successful development of new plant-parasitic nematode control strategies.

Technical feasibility of the research

As the primary nematology expertise of the NCR, the participants of this technical committee are capable of completing all proposed research as the objectives proposed utilize standard nematology techniques. As nematology experts, participants of this committee are capable of incorporating new nematode management technologies and ideas into a well-defined production system. Several members of this committee have substantial Extension appointments and are well-positioned to share committee findings with the public. Similarly, most committee members are also co-PIs on the United Soybean Board funded grant “SCN Coalition” to provide educational materials on SCN management to growers and agriculture industry stakeholders. To improve our ability to quantify economic impact, we have recruited Ray Massey and Ryan Milhollin, agricultural economists from the Univ. of MO with significant experience in quantifying the costs and returns associated with decisions farmers make under uncertainty.

The advantages for doing the work as a multistate effort

By working as a coordinated, multistate effort, data regarding geographical differences in nematode management and biology can be readily extrapolated and compared. This information in turn offers a broader understanding of plant-parasitic nematode interactions with their hosts and the soil environment, thereby allowing for more valuable insight into novel management strategies for improving yield and minimizing economic losses. For example, though SCN is present throughout the NCR (Tylka and Marett 2017), the response to some nematode-protectant seed treatments in areas may be attributed to interaction effects with additional geographically-restricted pathogens (Bissonnette et al. 2020). Understanding how soil edaphic factors, pest biology, agronomic practices, and other management strategies impact plant-parasitic nematodes is important at both the local geographical level and a regional level. Such work requires a multistate, coordinated effort by nematologists and plant pathologists to integrate novel strategies for nematode pest management. With the decrease in faculty in nematology and plant pathology at local land-grant institutions, collaborative nematology research is essential to maintain forward progress in the field and to continue providing relevant research results to stakeholders.

What the likely impacts will be from successfully completing the work

Increasing environmentally sustainable crop production through reducing yield loss caused by plant-parasitic nematodes is a key impact from this project. In corn and soybean alone, plant-parasitic nematodes are estimated to cause more than $1.5 billion US in economic losses annually (Allen et al. 2017, Mueller et al. 2020). Based on 2017 crop production data (UDSA NASS 2017), more than 8 million acres are chemically treated for nematode control in the NCR. This project will improve our understanding of integrated plant-parasitic nematode management in the near- and long-term through applied and fundamental research combined with outreach activities.