Managing sugar beet cyst nematode
Sugarbeet cyst nematodes can be managed by crop rotation, resistant variety, trap crops and improving soil health.
Managing sugarbeet cyst nematodes (SBCN) in the past 30 years has been extremely difficult. During that period, the number of sugarbeet cyst nematode positive fields has grown dramatically, resulting in significant yield loss and decreased profitability. The nematode spread and population increase has occurred because of several factors. Fields with long beet production histories certainly have increased risk. In Michigan, some beet producing areas have over 100 years of history of growing sugarbeets. As with most crops, the longer you grow them, there is more opportunity for pestilence to occur.
Short beet rotations have certainly allowed the pest to reproduce and build populations quickly. Each nematode is capable of two generations per year and each cyst may contain up to 300 eggs. The sugarbeet cyst nematode is uniquely equipped to lay dormant in the soil for years within its own protected armor called a “cyst.” Viability of cyst decreases as more years are put between host crops. Poor soil health also contributes to an increase of sugarbeet cyst nematode by decreasing the amount of beneficial organisms that may attack the nematode. Soil organic matter content is a large measure of soil health. Finally, the spread of nematodes has come from a variety of ways. Any way that soil can move will also transport nematodes. Blowing soil, returning tare dirt, or by hitching a ride on equipment and water are the most common modes. Be aware – every beet grower is at risk of this pest becoming a problem in their fields.
What can we do?
Many growers may have sugarbeet cyst nematode at low population levels which may not be impacting yields. A low to moderate population of nematodes may allow the beets to look normal, but still can reduce yields by one to three tons or more per acre. It is highly recommended that every sugarbeet field be soil and root sampled for the presence of sugarbeet cyst nematode. Ideal sampling times are middle to late summer in an existing sugarbeet field. Many times, the cyst can be seen on the roots during the growing season. Pay special attention to areas in the field where beet leaves will wilt during the mid-day heat and areas that exhibit nutrient deficiencies resembling nitrogen. Your agriculturist is well trained to help you identify the pest.
No single approach of managing sugarbeet cyst nematode is as effective as a multi-facetted effort. In some beet areas, there has been strong reliance on chemical control for improved yields. Longer beet rotations are helpful in lowering sugarbeet cyst nematode population in highly infested fields and will keep low infested fields from becoming high. Four year rotations should be considered the minimum. This alone, however, is not a cure-all and should be used in conjunction with other management practices.
Improving soil health can be achieved through use of cover crops, clover, manure and diverse rotations. By increasing organic matter, it helps increase soil fauna activity, which will help improve the balance of beneficial and antagonistic organisms. Oil seed radish is currently very effective as a sugarbeet cyst nematode trap crop. By planting this cover crop, the nematodes are tricked into hatching and then are unable to reproduce on the roots of the radish. This has been effective in lowering populations of sugarbeet cyst nematode by 80 to 90 percent and improving yields.
The newest tools that have become available in the last few years are sugar beet cyst nematode resistant varieties. Michigan Sugar Company, along with Sugarbeet Advancement, has been testing nematode resistant varieties. The results have been impressive with an average yield increase of 9.6 tons per acre in high population sugarbeet cyst nematode fields. As with any first generation variety, these new resistant releases may have other disease and trait weaknesses. Work closely with your agriculturist or seed dealer to know the strengths and weaknesses. However, used in the right field and managed properly, these varieties can make unprofitable fields productive again. Research has shown an additive effect of improved yields when management tools are combined such as incorporating extended rotations with oilseed radish or manure and a resistant variety.
In summary, management of sugarbeet cyst nematodes begins with minimizing the transport of soil from field to field. Long rotations are very helpful in keeping populations in check. Incorporate any practices that improve soil health and improve the populations of beneficial organisms. Utilize trap crops such as Colonel or Defender oilseed radish anywhere in the cropping rotation for an effective means of reducing sugar beet cyst nematode populations. The use of nematode resistant varieties can dramatically improve yields and minimize nematode reproduction. No single management practice is as effective as the combination of practices when managing this pest. Be aware all fields can be at risk, so be able to identify the pest, and be on the lookout in every field for signs and symptoms. Through early detection, management practices to keep the populations low can be effective.