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Ergot Found In S.D. Small Grain Fields

By Connie Strunk
 
The fungal disease known as ergot (caused by Claviceps purpurea), is developing in South Dakota wheat, rye, and triticale fields. Cool, damp spring weather during flowering followed by the warm/hot summer temperatures caused the ergot development.
 
Signs of Ergot Infection
 
The most common sign of ergot infection is the dark purple to black sclerotia (ergot bodies) found replacing the grain in the heads of cereal crops and grasses prior to harvest (Figure 1). On the plant, the sclerotia replace the developing seeds and can stick out past the glumes (Figure 2). There may be several sclerotia per head and they can be easily seen in grain samples when the crop is harvested. The ergot bodies may be the same size as the grain seed (typically seen in wheat) or in the case of rye, may be several times the size of the grain seed.
 
 
 
Fig. 1. Wheat infected with ergot. Sclerotia bodies are typically the same size as the wheat heads. 
 
 
 
Fig. 2. Rye infected with ergot. Notice the sclerotia at the middle of the rye head extending past the glumes.
 
Ergot Hosts
 
Ergot can be found in many different hosts including rye, triticale, wheat, durum, barley, oats, brome grass, foxtail, rye grass, crested wheat grass, orchard grass, timothy, and many other grasses. Ergot sclerotia may be present in or on the soil from previous hosts and can survive approximately one year in our area. The sclerotia may remain viable for several years in dry storage. There is a potential for ergot to develop every year but the weather is the key factor for infection to occur.
 
Marketing Problem
 
Ergot can be a marketing problem. The USDA Federal Grain Inspection Service grain standard, which is used by elevators, has defined ergot as a special grade (undesirable) for grain when the level of ergot exceeds 0.05% by weight.
 
Ergot Management
 
Plant sclerotia free seed. Control of ergot is said to begin with planting seed free of sclerotia. Certified seed can have no more than 2% maximum ergot sclerotia for the registered class and no more than 3% for the certified seed class. Seed producers typically do not want even that much, and wheat growers usually don’t want it either
 
Utilize crop rotation. In addition to planting clean seed another effective strategy is crop rotation. Avoid planting wheat near previously infested fields for one year, the approximate life span of the sclerotia bodies. The effectiveness of rotation to a non-susceptible crop will be diminished if grasses and grassy weeds in ditches and fencerows surrounding the field were allowed to head the previous year.
 
Clean the seed. Ergot can be cleaned out of the grain by using a gravity table. The grain can then be used or sold. Some shrink or loss of grain may be necessary to remove most of the ergot from the seed
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Wheat Yields in USA and China Threatened by Heat Waves Breaking Enzymes

Video: Wheat Yields in USA and China Threatened by Heat Waves Breaking Enzymes

A new peer reviewed study looks at the generally unrecognized risk of heat waves surpassing the threshold for enzyme damage in wheat.

Most studies that look at crop failure in the main food growing regions (breadbaskets of the planet) look at temperatures and droughts in the historical records to assess present day risk. Since the climate system has changed, these historical based risk analysis studies underestimate the present-day risks.

What this new research study does is generate an ensemble of plausible scenarios for the present climate in terms of temperatures and precipitation, and looks at how many of these plausible scenarios exceed the enzyme-breaking temperature of 32.8 C for wheat, and exceed the high stress yield reducing temperature of 27.8 C for wheat. Also, the study considers the possibility of a compounded failure with heat waves in both regions simultaneously, this greatly reducing global wheat supply and causing severe shortages.

Results show that the likelihood (risk) of wheat crop failure with a one-in-hundred likelihood in 1981 has in today’s climate become increased by 16x in the USA winter wheat crop (to one-in-six) and by 6x in northeast China (to one-in-sixteen).

The risks determined in this new paper are much greater than that obtained in previous work that determines risk by analyzing historical climate patterns.

Clearly, since the climate system is rapidly changing, we cannot assume stationarity and calculate risk probabilities like we did traditionally before.

We are essentially on a new planet, with a new climate regime, and have to understand that everything is different now.