Fighting the good fight against the sugar beet cyst nematode

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

The sugar beet cyst nematode is a major limiting factor in sugar beet production in Michigan. Sugar beet cyst nematode is a notorious robber of yield stealing as much as 10 or maybe 15 tons per acre. At $40 per ton with a loss of 10 tons per acre due to sugar beet cyst nematodes, if a field was over four acres in size, the theft would be considered a felony in Michigan. Of course, we all take steps to prevent theft of our material possessions. What about beet yields?

Until recently, crop rotation was really the only economically viable tactic for control of sugar beet cyst nematode in Michigan. However, a few years ago, BetaSeeds released two varieties with resistance to sugar beet cyst nematode and Michigan’s sugar beet growers reported some significant yield increases when growing these varieties. Really, since their release, state averages for yield have increased to record levels. Coincidence? Probably not. However, it would be inappropriate to acknowledge all this yield gain solely to control of sugar beet cyst nematode.

Growers should be prudent when using these sugar beet cyst nematode-resistant varieties. Where yields have improved, laboratory studies at MSU demonstrate that the nematode develops fairly well on these resistant cultivars. Five populations of sugar beet cyst nematode, collected during the survey of 2007 were tested on the resistant cultivars during the winter of 2008. To summarize the results after 56 days in a growth chamber, the average numbers of females and cysts found over the five populations were 123.60 on Prompt (susceptible control), 35.90 on Beta 1643N and 34.07 on Beta 5534N.

The cysts that formed on the resistant lines were smaller as the numbers of eggs and second-stage juveniles found averaged over the five populations were 264.8 on Prompt, 155.2 on Beta 1634N and 147.6 on Beta 5534N. Each average is the mean of four replications.

If the same parameter to assess resistance (average number of females on a resistant variety less than 10 percent of those on the susceptible check) is used for sugar beet cyst nematode as in a soybean cyst nematode type test (HG Type Test), neither Beta 1634N or Beta 5534N would be considered resistant based on the results of the bioassay conducted in the lab in 2008. Therefore, growers should monitor sugar beet cyst nematode numbers closely when using these resistant lines. These varieties do not have the same level of resistance against sugar beet cyst nematode that some soybean cyst nematode-resistant lines have versus that nematode. I would even go as far to speculate, that although yields have improved tremendously on sites where these resistant lines have been grown in Michigan, they still did not yield to their potential.

More sampling would help

So, how do we fight the good fight against sugar beet cyst nematode? Well, as with all nematodes, it starts with a strong sampling program as nematodes really are the hidden enemies. As one of two nematode diagnosticians at MSU, if I am to be blunt, I have to give Michigan’s sugar beet growers less than a passing grade when it comes to sampling. If I am to compare the annual number of sugar beet cyst nematode samples to the number for soybean cyst nematodes, taking into account the differences in acreage, beet samples still lag behind. There are possibly many plausible explanations, but the message is clearer to soybean producers to sugar beet growers. All successful cyst nematode sampling programs have a strong sampling component and fields should be sampled the fall before all soybean and sugar beet crops to minimize the risk of yield loss.

If sugar beet cyst nematodes are positively identified in samples, growers can use rotation, trap cropping and resistant varieties to manage the problem. Actually, by having effective trap crops (some cultivars of oilseed radish and mustards), sugar beet growers have an additional tactic available to them for cyst nematode management that soybean growers lack. Successful use of all three tactics should reduce the impact of sugar beet cyst nematodes in Michigan’s sugar beet fields. At least the goal should be to bring theft down to misdemeanor levels.

For questions or concerns about sugar beet cyst nematodes or any other nematodes, please contact Fred Warner (517-432-1333), Angela Tenney (517-353-8563) or Dr. George Bird (517-353-3890) at MSU Diagnostic Services. Nematode samples should be sent to Diagnostics Services. There is a $25 fee for a nematode analysis and a new $25 charge for species identification of cyst nematodes. Fight on.

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