BCN poses a serious threat to growers who cultivate sugar beet on infested fields. BCN may be more widespread than expected with infestations only being noticed in the crop when significant yield losses occur and is likely to become a greater problem in the future. In order to tackle this problem, a greater understanding of how the various types of sugar beet varieties yield under infestation is required to allow growers to make informed decisions on variety choice and, more importantly, how this will influence BCN populations in the future. Research has also been undertaken to assess the ability of BCN resistant brassica species to reduce nematode populations prior to planting sugar beet.
- To understand how susceptible, tolerant and resistant sugar beet varieties respond to infestation of BCN, particularly BCN reproduction levels on the varieties and yield quality differences.
- To investigate whether planting BCN resistant mustard and radish cultivars, prior to beet, encourages BCN hatch, hence reducing infestation of the following crop
- To investigate the impact of planting BCN resistant brassicas on the yield of the following sugar beet crop.
Outcomes / Key Message For Growers And Industry
Rotation length remains key to reducing BCN infestation levels. Cysts can retain viable eggs and juveniles that infest beet crops for over ten years following a suitable host crop (such as beet or OSR). A break of five or more years without a host allows for natural decline of nematode populations to less harmful levels, but there will still be losses in a susceptible beet crop.
The use of BCN tolerant varieties has become a popular option for control since their introduction in 2009 but their mechanisms of tolerance have been largely unknown. This PhD research has found that the tolerant varieties lead to significantly lower BCN populations than susceptible varieties but they cannot control BCN to the same extent as a resistant variety.
Resistant varieties have a smaller canopy per plant and take longer to reach canopy closure which explains their lower yields when previously tested in the UK. Increasing the seed rate of the resistant variety tested overcame the lower vigour shown and produced a similar yield to susceptible and tolerant varieties. Resistant varieties would be the best form of control for BCN and further investigations to their introduction to the UK might be beneficial for growers with high BCN populations.
Brassica hatch crops, planted in late summer, did not all produce significant reductions in BCN populations. Work is ongoing to understand the benefits of these brassicas and their interactions with BCN and is likely to require further trials in the future. Only some of the varieties currently available may be of benefit to use in the UK.