By Amanda Craven, Crop Sales Specialist
AGRIS Co-operative - Tupperville

With much of Ontario’s wheat marketed at the $7.00/bu mark and other commodities seeing lower values than “normal”, protecting the wheat crop from yield loss has never been more important. Manganese deficiency in winter wheat is found most commonly on sandy soils and is most noticeable either in the early spring, when root growth is limited, or when paired with other stressors such as cold temperatures, nitrogen applications, and fungicide/herbicide applications.

This year in the Tupperville area we saw a number of manganese deficient fields. The main giveaway in identifying this deficiency is fine leaf striping, pale plants and stunting.  Manganese aids in the production of chlorophyll, this is why deficient plants will appear pale in colour. The first call I received was about a wheat field that had been top dressed but hadn’t greened up yet. There was no burn to speak of, but the crop was struggling. After taking a walk through the field I noticed the plants were quite stunted and some striping could be observed. After digging up some plants I could see that root growth was also fairly limited. We treated this field within the week with 32% soluble manganese through the sprayer. Keep an eye out for temperature both the night before and after application. For foliar products temperatures below 2°C the night before and after application can cause crop injury.

Another call I received was about 28% burn on wheat (see figure 1 and 2). Nothing of grave concern, mainly cosmetic burn that the plant should grow out of but the grower was curious as to why there was so much damage this year. After a walk through the field there was some very noticeable striping, lower lignin content in the plant thanks to Mn deficiency had intensified the burn. We gave the field 10 days to grow out of the damage and then applied soluble manganese to the new growth.

Later on in the season that same field that I had my first call to had some Septoria present (see figure 3). This is likely due to the early season stress from the Mn deficient weakened the plants ability to fight off diseases. Similar to soybeans sometimes more than one foliar application of Mn is needed to address the problem. The wheat otherwise looked fantastic, lush green, lots of tillers. We treated it with a T1 fungicide (a normal part of the grower’s routine) and rolled on.

Manganese deficiency is concerning for a number of reasons. The lower lignin concentration in Mn deficient wheat means an increased risk of burn from 28% or chemicals, increased chance of leaf diseases such as Septoria, and greater susceptibility to cold stress. It also will limit chlorophyll production for photosynthesis.

You wouldn’t leave a Mn deficiency in soybeans left untreated; wheat should be handled the same way. This year wheat is considered a high value crop, it needs to be managed and protected accordingly. The window for application in this current crop has now past. These are observations for another year and lessons learned.