Plant-parasitic nematodes are one of the economically most important pathogens, and how rising soil temperatures due to climate change impact their ability to damage crops is poorly understood. The current study was conducted to evaluate the reproduction biology (reproduction and virulence) of Rotylenchulus reniformis and Meloidogyne floridensis on tomato at soil temperatures of 26 °C (control), 32 °C, 34 °C, and 36 °C. The reproduction and virulence of both nematode species were differentially impacted by soil temperature. Relative to the control, the increase in reproduction of R. reniformis ranged from 20% to 116% while that of M. floridensis ranged from 22% to 133%. The greatest reproduction of R. reniformis was observed at 34 °C while that of M. floridensis was observed at 32 °C. Across all temperatures, reproduction of M. floridensis was 2.9 to 7.8 times greater than the reproduction of R. reniformis, suggesting that the former nematode species has a greater fecundity. The rates of change in reproduction relative to the controls were greater in M. floridensis than in R. reniformis, indicating that the latter nematode species is more resilient to changes in soil temperature. The virulence of both nematode species increased numerically or significantly at 32 °C and 36 °C, but not at 34 °C. The greatest virulence of both nematode species was observed at 36 °C at which 57% and 60% root biomass was lost to R. reniformis and M. floridensis, respectively, compared to the root biomass of uninoculated plants at that temperature. The results of the current study suggested that crop damage by nematodes will likely increase as global soil temperature continues to increase.

Two peach rootstocks (‘Guardian’ and ‘MP-29’) and ten winter cover crops (rye, wheat, barley, triticale, oat, Austrian winter pea, crimson clover, balansa clover, hairy vetch, and daikon radish) were evaluated in a greenhouse environment to determine their suitability to host ring nematode, Mesocriconema xenoplax. Each crop was inoculated with 500 ring nematodes, and the experiments were terminated 60 days after inoculation. The reproduction factor (ratio of final and initial nematode population) ranged from 0 to 13.8, indicating the crops greatly varied in their host suitability to ring nematode. ‘Guardian’ has been known to tolerate ring nematode; however, results from the current study suggest the tolerance statement is anecdotal. Another peach rootstock, ‘MP-29’, was also a good host for ring nematode, suggesting an urgency to develop ring nematode-resistant peach rootstocks. Wheat supported the least to no nematode reproduction while pea supported the greatest reproduction. The rest of the cover crops were poor to good hosts to ring nematodes. Although planting cover crops in peach orchards is not common, employing non or poor host crops can help suppress nematodes in addition to having soil health benefits. Furthermore, peach breeding programs should focus on finding and introgressing ring nematode resistance in commercial rootstocks.

Greenhouse experiments were conducted to determine the host suitability of ten summer cover crops and two peach rootstocks to Meloidogyne floridensis by inoculating them with 10,000 M. floridensis eggs. Brown top millet and sunn hemp were nonhosts as they did not support nematode reproduction. Buckwheat, cowpea, pearl millet, Japanese millet, and sunflower supported more than 25,000 eggs/pot, which indicated that these crops are good hosts to M. floridensis. The crops that supported poor nematode reproduction were sesame, grain sorghum, and sorghum-sudangrass, with their reproduction ranging from 219 to 7,750 eggs/pot. In addition to having many galls on the roots, the peach rootstock Guardian had 10,100 eggs on the roots and 450 second-stage juveniles in the pot, which indicated that ‘Guardian’ is a good host to M. floridensis. Although the nematode reproduction on MP-29 rootstock was relatively lower, the presence of many large galls on the roots indicates MP-29 is susceptible to M. floridensis. Results from the current study suggest that the employment of nonhost cover crops and poor-host rootstocks could aid in effective nematode management programs for peaches.

The guava root-knot nematode (Meloidogyne enterolobii) is a highly aggressive species of root-knot nematode that is not manageable with currently existing nematode management methods. This study was conducted to evaluate the suppressive ability of winter cover crops against M. enterolobii. Eleven winter cover crops (rye, wheat, barley, triticale, oat, Austrian winter pea, crimson clover, balansa clover, hairy vetch, purple top turnip, and daikon radish) were evaluated against M. enterolobii in a growth room environment. Root-knot nematode-susceptible tomato (Solanum lycopersicum cv. Rutgers) was used as a control. Nematode reproduction on cover crops ranged from 1 to 501,373 eggs/g root, with oat supporting the least nematode reproduction and crimson clover supporting the greatest nematode reproduction. The crops significantly suppressing egg production on roots and second-stage juveniles in the soil relative to the control were oat, winter pea, wheat, barley, rye, and triticale. Hairy vetch, purple turnip, daikon radish, and crimson clover were good hosts, while balansa clover, wheat, winter pea, barley, rye, triticale and oat were poor or non-hosts, with the latter four crops producing substantial biomasses. Employment of these cover crops that suppress or do not support M. enterolobii reproduction while adding substantial biomass to the soil may lead to sustainable nematode management.