1: Root-knot nematode host status and susceptibility of different hemp cultivars

Since its removal from the controlled substance list, hemp (Cannabis sativa L.) is now an agricultural commodity in the US and interest among growers is high. Florida growers are increasingly interested in new alternative crops as many traditional crops in Florida are facing progressively more pressure due to disease issues and increasing competition from abroad. Nematodes, especially root-knot (Meloidogyne spp.) and sting nematodes (Belonolaimus longicaudatus), are considered one of the main limiting factors to crop production in Florida because of the subtropical climate and often sandy soils; therefore, when introducing new crops to the state, it is important to know their nematode host status. A greenhouse study was set up to evaluate the host status and susceptibility of six hemp cultivars to a mixed population of Meloidogyne spp. Each cultivar was evaluated with and without nematodes. Those with nematodes had two plants per pot, where one plant was sampled after one week and roots were stained for evidence of nematodes. After 60 days, roots were rated for root galls, root-knot eggs were extracted from roots, juveniles were extracted from soil, and biomass (height and weight) measurements were taken. Root-knot nematodes reproduced well on all six hemp cultivars. Plant biomass was not negatively affected but root dry weight was reduced in some cultivars. To support the future viability and sustainability of hemp, and considering the importance of nematodes in Florida, it is critical to assess the impact that root-knot and other nematodes may have on this crop.