Diseases of Alfalfa - Non-Infectious

What to look for?.
Small white spots develop on the margins of leaflets. Bottom leaves yellow and die. One ton of alfalfa removes 40 to 50 lbs of potassium from the soil. A 5 ton crop over 200 lbs per acre of K₂O.

Photo: Howard

Picture description White spots on leaves.

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Management strategy
Apply adequate potash fertilizer.
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P Deficiency

What to look for?.
Leaves may be small and dark colored often with a red or purple hue. A 5 ton crop of alfalfa removes 50 lbs of phosphate per acre. Boron deficiency in the form of leaf yellowing also shows up on irrigated sandy soils.

Alfalfa may fix nitrogen effectively. A 5 ton crop may fix over 200 lbs of N. But remember the huge quantities of macro and micronutrients that is used with each annual crop. All these minerals must be replaced if yield is to be maintained.

Photo: Richard

Picture description Red color of alfalfa leaf showing phosphate deficiency.

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Management strategy
Fertilize according to crop removal and crop yield expectations.

Drought

What to look for?
Wilted patches of alfalfa in a field during dry season often indicated the presence of solzonetzic pans that confine the alfalfa roots to the top few feet of soil. Individual wilted plants are usually the work of pocket gophers or perhaps Verticillium wilt.

Photo: Richard

Picture description Wilted alfalfa plant

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Management strategy
Deep ploughing can break up shallow solzonetzic pans.

Frost

What to look for?
Frost particularly in late August or early September can severely damage alfalfa stands.
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Photo: Smith

Picture description Severe frost injury.

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Management strategy
Heavily frosted crops should be swathed as soon as possible to retain nutrients.

Photographs and information assembled and prepared for ARD by Dr. Ieaun R. Evans Agri-Trend Agrology Ltd.

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