Sugarbeet growers need to select oilseed radish varieties carefully

Defender oilseed radish will reduce sugarbeet cyst nematode populations. Commonly sold tillage radish types will increase sugarbeet cyst nematode populations.

Sugarbeet cyst nematodes were detected in one out of four fields in a random survey of Michigan sugarbeet fields completed in 2007. Yield losses from sugarbeet cyst nematodes have been documented up to 15 tons per acre. This pest can be managed by lengthening beet rotations, incorporating oilseed radish trap crops and using tolerant varieties. Any practices that improve soil health including cover crops will be beneficial.

Oilseed radish has become a popular cover crop in the sugarbeet growing areas as a nematode trap crop and to improve soil health and drainage. It is important to understand that all oilseed radish varieties have shown deep root penetration. There are several varieties currently marketed as a tillage radish. There is only one variety (Defender) that is currently marketed as a nematode trap crop that should reduce sugarbeet cyst nematode population densities. This should be the only variety that sugarbeet producers use in their crop rotation. Most other tillage or oilseed radishes are excellent hosts for sugarbeet cyst nematodes and will increase populations.

In 2012, a growth chamber study was implemented by Fred Warner, nematode diagnostician at Michigan State University, comparing sugarbeet cyst nematode development on several oilseed radish varieties being marketed. This study confirmed that Defender was the only variety that almost completely reduced sugarbeet cyst nematode development (Table 1). The other radish varieties tested had as many or more sugarbeet cyst nematode females on the roots as did the sugarbeet check.

Table 1. Sugarbeet cyst nematode development on several oilseed radish varieties

Radish cultivar

Number of sugarbeet cyst nematode females

Soilbuster

220

Groundhog

184

Graza

135

Driller

211

Daikon

197

Tillage

262

Defender

0.25

Prompt (sugarbeet variety)

177

If you have known sugarbeet cyst nematode fields, it is recommended that an oilseed radish trap crop be utilized somewhere in the rotation prior to sugarbeet planting. A sugarbeet cyst nematode resistant-beet variety should also be utilized at planting to maximize yield. The best timing for establishing an oilseed radish cover crop is usually in early to mid-August. Establishment at this time generally will follow harvested wheat. Wheat fields should be worked and have 75 to 100 pounds of nitrogen per acre applied. Oilseed radish sowed after pickles or early harvest of dry, edible beans is also an option.

Later planted September seeding generally does not produce as much vegetative growth because of shortened growth period and cooler weather. Trap crop seeding rates should be approximately 20 pounds per acre with a grain drill.

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