Chlorotic dieback of flax grown on calcareous soils

Flor, H.H.

Chlorotic dieback of flax grown on calcareous soils

1943

Flor, H.H.

Chlorotic dieback, a nonparasitic disease of flax, is associated with certain unproductive soil areas in the Red River Valley of North Dakota. When flax is grown experimentally in soils representing successively deeper soil layers, the disease is least severe in surface soil and increases in severity for each successively lower horizon. Chemical tests of soil from an unproductive area, as well as the growth of flax in such soils that had been steamed, or leached, failed to indicate the presence of a toxic substance. Flax grown in unproductive soils to which mineral amendments had been added responded favorably to the addition of phosphate. The chlorotic phase of the disease was more pronounced in the wetter soils, but plants grown in both wet and dry soils were stunted and showed symptoms of leaf necrosis and stem dieback. The disease symptoms were most severe at low soil temperatures and showed progressive diminution in intensity with rise in soil temperature ranging from 12 degrees to 25 degrees C. Flax growing in unproductive soil responded more favorably to increases in soil temperature than did that growing in productive soil. Applications of phosphate to the Bearden silt loam corrected its unproductiveness and the chlorotic dieback symptoms. Similar applications to the Fargo clay soil were only partially corrective. It is suggested that the flax trouble at low soil temperatures is caused, at least in part, by deficiency or unavailability of essential minerals, especially phosphate, in the highly calcareous alkaline soil.

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