Fungicide and Increased Yields

Overview:
In 2005, the chemical company BASF began to publish corn yield data which showed significant yield increases after treatment with their flagship product, Headline (active ingredient pyraclostrobin).

Very quickly, other fungicides were being tested and publicized, and many more impressive corn yield increases were documented. BASF's latest flyer (PDF, 1.1 MB) says they now have 3,000 on farm yield tests which average 12-16 bushel per acre yield increases.  In many regions, large numbers of acres of corn are being treated every year, most often with aerial application.

In the last two years, studies have shown increased yields in wheat, sunflowers, and soybeans with fungicide usage, and BASF claims more than 10 bushels per acre in wheat when treated at flag leaf stage. Treatment is more likely to pay dividends in susceptible varieties, in irrigated wheat, and in minimum till or no-till wheat. Here's a BASF fact sheet on wheat treatment.

Wheat:
On wheat, economic levels are more likely to be reached when wheat prices exceed $3.50-$4.00 per bushel, and in fields with a yield potential of 45-50 bushels per acre.

In 2009, prices on some of the tebuconazoles dropped dramatically and wheat prices were in the $5 per bushel range. This changed the equation significantly: a few years ago, applied prices for fungicides were $20-$25 per acre, and on $2 per bushel wheat, there was not much interest.  But with wheat at $5 per bushel and applied fungicide prices under $10 per acre, the break-even yield increase dropped from 10-12 bushels to only 2 bushels per acre.

There are many wheat fungicide choices, including Tilt, Tebuzol, Monsoon, Orius, TwinLine, Stratego, Headline, Quadris, and Bumper. Some have dual modes of actions, which may be preferred if you have susceptible varieties and high disease pressure. Prices vary dramatically, and wheat price and expected yields also dictate choice, as noted above. Here is a chart comparing some of these products on different diseases (PDF, 39KB)  As you can see, the lower priced tebuconazoles mentioned above perform quite well..

To read KSU's most recent ratings on the disease susceptibility of many common wheat varieties, click here. (PDF file, 68 KB) 

To read more about wheat diseases, click here.

BASF offers several  wheat products, with Twinline being the most prominent.  Twinline offers two active ingredients:: pyraclostrobin and a triazole. BASF argues this can provide improved disease protection, but it is also more expensive.

Corn:
Most crop consultants and university tests agree that disease-susceptible corn and corn which is exhibiting disease symptoms will respond well to a timely fungicide treatment. Less unanimous is agreement with the argument, made by BASF and others, that a "plant health" effect occurs. Essentially, BASF says that pyraclostrobin can increase yields due to improved nitrogen use efficiency and greater photosynthesis, even when disease is not present. It is possible that yield increases occur because control of loww levels of disease results in yield increases greater than previously thought.

In the case of corn yield increases, larger ears and reduced lodging are most obvious, and in some cases, the plant remains green longer in the late season. The biggest yield increases have been found on the higher yielding varieties, and in disease susceptible varieties, especially under irrigation or in humid climates. The fungicide is commonly applied at tasseling, and can be applied with insecticides.

Test plots in our area have shown initially encouraging responses from farmers on wheat tests, but the disastrous harvest conditions on corn in 2008 limited feedback on fungicide efficacy.  

The obvious places to try fungicide are on high yield potential fields, with disease susceptible varieties, and under irrigation or when weather conditions are humid. Certainly, if a crop is displaying disease symptoms, applying fungicide makes sense.
 
If you'd like to read BASF's Headline fact sheet, click here. (PDF, 2 pages, 909 Kb). Another impressive document is Mike Hofer's presentation, which shows graphs of yield tests, photos of treated and untreated corn, and high quality photos of the various corn diseases.  Click here. (PDF, 18 pages, 2,600 Kb).