As of June 30th, 19.3% of Western Iowa is considered abnormally dry and according to the forecast will continue to get drier. During the normal course of

growing, corn and soybean plants photosynthesize and with the exchange of CO2 and O2 through the stomata the plants give off water vapor in a process called transpiration. In fact, according to the USGS an acre of corn can transpire 3,000-4,000 gallons of water each day. Transpiration rates are affected by many things including temperature, humidity, sunlight intensity, precipitation, soil type and saturation. In a normal year plenty of water falls in Iowa and little thought is given to this process. Conversely, in a year where water is at a premium anything that can be done to help the plants conserve water can translate into yield gains.

The question has come up should one continue to invest in a crop if it is going turn off hot and dry and will the fungicide help in water conservation? The answer to this question is undoubtably yes. The strobilurin chemistries have for a long time been known to help plants reduce transpiration and the same goes for the new SDHI chemistries, Solatenol in Trivapro fungicide and Adepidyn in Miravis Neo fungicides=.

Several studies were then conducted to see if these new fungicides provided the same or more plant health benefits as some of the older strobilurin fungicides. One of those studies was conducted by J. Leipner and published in ASM Biology Research in 2015 (figure 3) and showed that transpiration was reduced by up to 40% compared to the untreated check and did NOT affect photosynthesis. That means that the plant had the best of both worlds by

staying at peak photosynthesis while conserving water. Additionally, Leipner found out this was rate dependent. Meaning that maximum water conservation occurred at the highest rate studied. 

Another way to measure stress on a plant is to use a hyperspectral analyzer or Lab Spec 4.
This tool measures different wavelengths of light that cannot be seen with the naked eye.
One of the things that it can measure is plant water content. In figure 4 the Lab Spec 4 was
used to take readings on drought stressed plants that were treated and untreated with different fungicides. In this case Quilt Xcel (combination of a strobilurin and triazole fungicides) and Adepidyn (SDHI fungicide) which is found in Miravis Neo were studied. The study showed significantly better vegetative index in both fungicide treated plants compared to the untreated. 

What does this mean to the average grower? Fungicides not only help protect the plant from disease they will also help maintain proper growth and function within the plant during times of water stress which will in turn lead to yield protection. 

Visit KnowMoreGrowMore.com, a place to learn more to enable you to grow more. Join the conversation online - connect with us at social.SyngentaUS.com

AUTHORED BY:

Dean Grossnickle, Agronomic Service Representative Central Iowa
Randy Kool, Agronomic Service Representative Western Iowa
Zach Trower, Agronomic Service Representative Eastern Iowa