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Cold spring causes cold injury and nutrient deficiency symptoms in field crops

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Crop samples are starting to come into the Schutter Diagnostic Clinic and my phone is buzzing a lot more these days. Thank you all for reaching out! This year’s cold spring is giving our crops a slow start and a lot of what I see in the diagnostic lab is related to cold temperatures and nutrient deficiencies. This AgAlert includes a summary of what to look out for these days.

Quick Summary for Busy People

  • This spring has been unusually cold, which is slowing plant growth. Be patient.
  • Color banding is a common symptom of freeze injury in spring-sown seedlings. Burned leaf tips and bleached, wilted-looking leaves (or leaf sections) are also typical. Depending on the crop growth stage, temperature low and duration of low temperatures, the damage from cold/freeze injury may range from cosmetical to yield-limiting.
  • Cold soils limit nutrient uptake. We’ve seen symptoms of nitrogen, iron, and zinc deficiency. Nutrient deficiency could further be compounded by root rot issues.

 

  1. Cold injury/stress

This spring has been quite cold and crops are slow to resume growth. I have received questions on alfalfa not resuming growth this spring. I heard reports on spring sown cereal crops looking stunted and yellowish, sometimes having twisted leaves (Figure 1). While there may be other reasons, the cold temperatures and cool soils are certainly slowing crop progress. Pant nutrient acquisition is limited in cool soils, which is why crops may appear nutrient deficient (see below). Have a little patience. The plants should grow out of it once the soil warms up. Following is a discussion of more specific cold and freeze injury symptoms by crop and developmental stage.

Wheat: Freezing temperatures during the spring may cause color banding on spring-sown seedlings when warm days are followed by cool nights. You may observe yellow, white, brown, or even purple bands on the young leaves, which often occur at the same height on neighboring seedlings. Freezing temperatures can also cause leaf tips to turn yellow and necrotic (Figure 1). These types of injury are cosmetic and the plants will grow out of it. During stem elongation, cold temperatures may damage the stem and cause it to split or cause damage to the vascular system (water and nutrient transport), which will cause the stem to collapse and lodge. The damaged area on the stem may be bleached and water-soaked. The growing point or spike may be damaged with few symptoms on the stem. The emergence of chlorotic leaves from the whorl may indicate that the developing spike has been killed. More leaves will become chlorotic as the culm deteriorates. Emerging heads may be trapped or may have “frosted tips” (Pun intended! Couldn’t help it.). Don’t confuse frost tipped heads with head blight. Further information on freeze injury symptoms in wheat can be found in the publication from Kansas State University “Spring Freeze Injury to Kansas Wheat”, including a neat table of primary symptoms of freeze injury to wheat at spring growth stages and its effect on yield

Barley: Frost damage during stem elongation can damage the developing heads and result in shriveled, deformed, and pale heads. More information on freeze injury symptoms in barley (and oats) can be found in the “Frost identification guide for cereals” published by the Government of Western Australia Department of Primary Industries and Regional Development and the Grains Research and Development Corporation.

Pulses: One of the most obvious symptoms of freeze injury to young pea plants is the death of the growing point. The most recognizable symptom of freeze injury on pea leaves is the death of interveinal tissue, which appears water-soaked at first and then turns necrotic brown (Figure 2). Chickpeas are generally more sensitive to freeze injury than lentils. From a distance, the top leaves of injured plants turn yellow to white and appear dry. Sometimes only the leaf margins dry up and appear scorched without developing lesions of definite shape or size. More information on freeze injury symptoms in pulse crops (canola, and lupine) can be found in the “Frost identification guide for canola and pulses” published by the Government of Western Australia Department of Primary Industries and Regional Development and the Grains Research and Development Corporation.

 

  1. Nutrient deficiency.

The cold soils make it difficult for plants to acquire nutrients. You may see stunted plants that look pale green or yellow. Chlorotic (yellow) leaves can indicate nitrogen deficiency, which first expresses at the older (lower) leaves, moving from the leaf tips to the base (Figure 3). Iron deficiency causes yellow leaves with green stripes along the leaves’ length and could be confused with virus infection (Figure 3). Zinc deficiency expresses very similar to iron deficiency. Iron deficiency is very common in high pH soils. Foliar applications of nutrient solutions containing iron may be beneficial, but the plants usually recover just fine once they start growing. Leaf yellowing and stunted plant growth could also be caused by root rots, and often we observe compounding effects of two or more factors.

 

Picture Captions

Figure 1. Twisted leaves (left) and yellowing and necrotic leaf tips (right) due to cold injury. Picture courtesy Mary Burrows, Montana State University.

Figure 2. Freeze injury to young pea plant. The leaves are scorched and dead. Picture courtesy Mary Burrows, Montana State University, Bugwood.org.

Figure 3. Evenly yellowing leaves from the leaf tip to the base with older leaves being affected first is an indicator of nitrogen deficiency (left). Yellow leaves with prominent green veins are a symptoms of iron or zinc deficiency (right). Picture courtesy (left) https://www.agric.wa.gov.au/mycrop/diagnosing-nitrogen-deficiency-wheat; (right) Juliet Marshall, University of Idaho.

 

Please don’t hesitate to email (uta.mckelvy@montana.edu) or call (406-994-557) if you have any questions. I’m here to help. If you’re unsure about the symptoms you are observing, bring a sample to your local Extension agent or submit one to the Schutter Diagnostic Lab.

Best,

Uta McKelvy, Extension Field Crop Pathologist

Phone: (406) 994-5572

Email: uta.mckelvy@montana.edu