Carrot (Daucus carota) is an important crop grown in Canada and globally. Fresh market carrots have strict cosmetic requirements to command full value at Grade A and are frequently downgraded for irregular shape, size, or pest damage. Organic farming presents challenges for nutrient management, soil health and pest control, which may be mitigated with cover cropping. A 3-year field experiment was conducted on a commercial organic farm to 1) test the effects of six preceding-year cover crop treatments compared to a weedy fallow control on carrot yield and quality, wireworm damage, reasons for downgrading, and populations of plant parasitic nematodes, and 2) characterize within-farm spatiotemperal variability in production to identify strategies to improve and stabilize economic return. Carrot yield (42-55 Mg ha-1), quality (39-92% Grade A) and market value (183-221 $1000 Canadian dollars ha-1) varied drastically across years, and blocks within years (<= 20% differences), but cover crops had no impact on these metrics. The dominant reasons for downgrading were morphological, affecting 7-74% of carrots each year and varying with cover crop only once, where carrots following buckwheat (Fagopyrum esculentum) had fewer shape flaws. Nematodes had no relationship to cover crop or any carrot metric and wireworms damaged only 2% of carrots across all three years. This study found virtually no effect of cover crop species composition on next year's carrots on this farm, and that the farmer-collaborators can optimize their operation by improving crop establishment across space and time, reducing morphological flaws, and seeking higher value for downgraded produce.

Colorado potato beetle, Leptinotarsa decemlineata, wireworms and white grubs are important pests of potato that are challenging to manage. This study evaluated three endemic entomopathogenic nematodes (EPNs) (Steinernema carpocapsae 'NY01', S. feltiae 'NY04', and Heterorhabditis bacteriophora 'Oswego') as biocontrol agents against L. decemlineata, wireworms and white grubs in New York. The efficacy of individual EPN species and their combinations on L. decemlineata larval mortality was assessed via soil-based bioassays in the laboratory. Additionally, L. decemlineata survival and percentage of tubers damaged by wireworms and white grubs were evaluated in field trials in which combinations of pairs of EPN species were applied to the soil at least one month prior to initiating the experiment. Results from bioassays indicated that among the three EPN species, L. decemlineata late instars were most susceptible to H. bacteriophora 'Oswego'. Additionally, larval mortality was generally higher (14% on average) using pairs of EPN species compared to single species. Soil applications of pairs of EPN species prior to potato planting did not affect L. decemlineata adult survival either during the summer or following spring. However, tuber damage caused by wireworms and white grubs was reduced by 40% using a combination of H. bacteriophora 'Oswego' and S. feltiae 'NY04'. Overall, EPNs applied in soil have potential as biocontrol agents for soil-dwelling pests like wireworms and white grubs in potato, and their efficacy also may extend beyond a single cropping season, but do not seem to be an effective tool for L. decemlineata management in potato.

Click beetle larvae have been observed to cause crop damage in various regions worldwide; however, accurate prediction of plant damage is hindered by their subterranean life cycle and the associated challenges in sampling. Melanotus senilis, a beetle belonging to the subfamily Elaterinae (tribe Melanotini) within the family Elateridae, is a destructive agricultural pest that harms maize, hops, and ginger. Our study presents novel evidence indicating the attraction of M. senilis larvae to Citrus natsudaidai (Japanese name Natsumikan or Natsudaidai). Through a field experiment involving different citrus fruits, namely natsumikan, oranges, and grapefruits, we found that C. natsudaidai attracted the highest number of M. senilis larvae. Furthermore, in a separate experiment in which C. natsudaidai and potatoes were placed in the field, C. natsudaidai significantly outperformed potatoes in attracting M. senilis larvae. These findings suggest that C. natsudaidai fruit placed on the soil surface attracts M. senilis larvae. C. natsudaidai fruits used in this study were sourced from those that remained unharvested until August. Therefore, it is possible that the C. natsudaidai fruits used for comparison were more mature than the citrus fruits used in this study. It is possible that the ripening of C. natsudaidai may have led to changes in CO2 and ethylene emissions, potentially attracting a greater number of M. senilis larvae. Further research is required to explore these aspects in detail.