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Fallow Syndrome after Sugarbeet (06/07/18)

In the Grand Forks area and north, there are fields of corn planted into 2017 sugarbeet fields that are experiencing fallow syndrome symptoms (see figure).

Fallow Syndrome after Sugarbeet

In the Grand Forks area and north, there are fields of corn planted into 2017 sugarbeet fields that are experiencing fallow syndrome symptoms (see figure).

Fallow syndrome is so-called because the condition, which is stunting with a purple leaf/stem color especially early in the growing season and subsequent yield loss, was historically seen after black fallow. Mycorrhiza is a symbiotic fungi that extends the effective root system of a supportive plant by means of its root-like hyphae strands. Mycorrhiza is important for corn to gather the phosphorus (P) it requires most efficiently. Black fallow, and the cultivation of non-mycorrhizal crops in the Cruciferae (mustard) and Chenopodiaceae (lambsquarter) plant families result in low mycorrhiza survival into the next crop year. Our Cruciferae crops are canola, mustard, and forage radish. Our Chenopodiaceae family crop is sugar beet. Crops particularly susceptible to fallow syndrome are flax and corn.

franzen.1

Fallow syndrome is not uncommon after sugar beet, but it has been at least 15 years since I have seen symptoms this severe. I think that over that time our May seasons have been relatively cool, and the above-ground corn growth has been suppressed by the temperatures, allowing time for the mycorrhizal populations to increase before rapid demand of P by the corn occurred. This year, our very warm temperatures have increased early demand for P, and that is why I think we see such severe symptoms.

An additional factor for the severity of symptoms is that most P taken up by sugarbeet is returned to the soil during harvest leaf mowing. The leaf tissue rapidly decomposes and much P is returned to the next crop in an organic P form. This year, the northern Valley experienced a series of severe dust storms. Significant soil was lost from many areas, which is also the soil containing much of the organic P from the sugarbeet leaves. In past years, with not as much soil loss, the organic P remaining may have decreased the P deficiency caused by fallow syndrome to corn, while this year much of the organic P probably left the field for places much farther east.

In the future, it would be best for corn growers not to follow sugar beet with corn. I think that some growth drag also occurs with soybean and small grain after sugar beet, but it is small and no symptoms are ever seen. If corn is to be grown, the only remedy is to apply 150 pounds per acre of 11-52-0 (MAP) or equivalent P rates of other fertilzers in a 2X2 inch band. Any safe rate of fertilizer in furrow is not enough to overcome the lack of mycorrhiza and provide early season P nutrition to corn. No P fertilizer was applied at planting in the field pictured.

 

 Dave Franzen

NDSU Extension Soil Specialist

701-799-2565

Joel Ransom

NDSU Extension Small Grain/Corn Agronomist

701-231-7405

 

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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