**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** ROOT-LESION NEMATODES OF THE GENUS PRATYLENCHUS ARE AN ECONOMICALLY IMPORTANT GROUP OF PLANT-PARASITIC NEMATODES. TWO SPECIES OF ROOT-LESION NEMATODES, PRATYLENCHUS PENETRANS AND P. NEGLECTUS , ARE RANKED AMONG THE MOST ECONOMICALLY DEVASTATING SOILBORNE PATHOGENS AFFECTING CROPS BECAUSE OF THEIR WORLDWIDE DISTRIBUTION, BROAD HOST RANGE AND INTERRELATIONSHIP WITH OTHER PESTS (AGRIOS, 1969; NICKLE, 1984). PRATYLENCHUS SPP. ARE MORPHOLOGICALLY IDENTIFIABLE TO THE GENUS LEVEL, CHARACTERIZED BY THEIR STOUT STYLET AND DISTINCT OVERLAPPING ESOPHAGUS. HOWEVER, MORPHOLOGICAL IDENTIFICATION OF THESE NEMATODES TO THE SPECIES LEVEL REMAINS A CONSIDERABLE CHALLENGE EVEN TO EXPERIENCED AND WELL-TRAINED NEMATOLOGISTS. FOR NEARLY TWO DECADES, A RANGE OF AGRICULTURAL EXPERTS FROM MICHIGAN STATE UNIVERSITY HAVE OBSERVED SPORADIC, BUT SERIOUS ROOT-LESION NEMATODE DAMAGE IN SEVERAL MICHIGAN CARROT FIELDS. UPON BRIEF SOIL ANALYSIS, IT WAS DETERMINED THAT ROOT LESION NEMATODE POPULATIONS DID NOT EXCEED KNOWN ECONOMIC THRESHOLDS. AT THAT TIME, IT WAS HYPOTHESIZED THAT THIS INCREASED DAMAGE WAS DUE TO AN AGGRESSIVE SUB-POPULATION OF P. PENETRANS RATHER THAN AN INCREASE IN NUMBERS (BIRD AND WARNER, 2018) . HOWEVER, AFTER USING MOLECULAR MARKERS TO IDENTIFY THESE NEMATODES RECENTLY, WE DISCOVERED THAT THESE WERE IN FACT TWO DISTINCT SPECIES OF PRATYLENCHUS: P. PENETRANS AND P. NEGLECTUS THAT ARE CAUSING DIFFERENT LEVELS OF DAMAGE IN MICHIGAN CARROT FIELDS. OUR CURRENT HYPOTHESIS IS THAT AT SIMILAR POPULATION LEVELS, P. PENETRANS CAUSES MORE AGGRESSIVE DAMAGE ON CARROT FARMS COMPARED TO P. NEGLECTUS . DAMAGE BY P. NEGLECTUS, HOWEVER, SHOULD NOT BE DISPARAGED AS IT CAUSES SIGNIFICANT ECONOMIC LOSS ON POTATO AND WHEAT IN THE US ( HAFEZ ET AL.1999). IN MANY STATES, WHEAT IS COMMONLY USED AS A ROTATIONAL CROP OR AS A COVER CROP TO PROTECT CARROT SEEDLINGS. THE MISIDENTIFICATION OF PRATYLENCHUS SPP. MAY BE OCCURRING IN MANY DIAGNOSTIC LABS, WHERE IDENTIFICATION IS DONE BASED ON MORPHOLOGICAL CHARACTERS ONLY TO THE GENUS LEVEL. THE KEY FOR MANAGING THESE TWO PRATYLENCHUS NEMATODE SPECIES IS PROPER IDENTIFICATION AND UNDERSTANDING OF UNDERLYING MECHANISMS THAT CAUSE DAMAGE TO DIFFERENT HOST PLANTS. THIS WILL LEAD TO THE DEVELOPMENT OF SPECIFIC INTEGRATED STRATEGIES FOR THE CONTROL OF EACH NEMATODE SPECIES IDENTIFIED, RATHER THAN THE CURRENT NON-TARGET APPROACHES WHICH CAN BE COSTLY AND INEFFECTIVE. IN THIS PROJECT, OUR MAIN GOALS ARE (1) TO HELP CARROT AND WHEAT GROWERS CORRECTLY IDENTIFY LESION NEMATODE POPULATIONS IN THEIR FIELD TO SPECIES AND TO DEVELOP EFFECTIVE WAYS TO MANAGE EACH SPECIES FOLLOWING AN INTEGRATED APPROACH; (2) TO COLLABORATE WITH CARROT GROWERS, WHEAT GROWERS, AND EXTENSION FACULTY AT VARIOUS UNIVERSITIES ACROSS THE NATION TODELIVER THE FINDINGS OF THIS PROPOSAL TO GROWERS.