June 11th, 2021

posted by Andrew Blomme on 6/11/2021 in Weekly Newsletter

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June 11th, 2021

Weekly Weather Update

The past 7 days have been the warmest week of the year up to this point. The high temperatures have sped up crop development this week. Our area accumulated 165-182 GDU's depending on your specific geography. Historically, the second week of June averages about 130 GDU's accumulated. As a result, this week we were well above average in terms of corn development. 

The above average temperatures we have received and the below average rainfall are starting to effect crop growth in some areas. The map below shows precipitation from this year compared to average. Last year, dry conditions were localized to pockets of western Iowa. This year dry conditions are much more widespread. 

Precip Departure

The next map shows average daily high temperatures for the past week. The trend shows highest temperatures in NW Iowa working down to lower daily temperatures in SE Iowa. 

Average Daily High Temps

The next map is the drought monitor map for the state of Iowa. You can see the same trend of severe drought conditions in NW Iowa working down to no drought conditions in SE Iowa. This trend follows the trends of the two maps above fairly closely. With the 10 day forecast trending warmer and drier, it is likely that we will see changes in the drought monitor map.

Drought Monitor Map

If recent trends continue, water stress will not be uncommon this summer. Iowa State released an article discussing the effect of drought stress in corn and soybeans at different growth stages. You can find that article at the following link: Iowa State Extension-Influence of Drought Stress in Corn and Soybeans

Corn Approaching V6

V6 is an important stage in a corn plant's lifecycle. Even though we are several weeks away from tassels appearing, at V6 a corn plant is done creating vegetative structures and is starting to create reproductive structures, such as ear shoots and a tassel. At V6, a corn plant has already created all of the leaves it will ever have. You could dissect a plant and find all its leaves wrapped tightly around each other. From now until tassel, all the plant has to do is grow those leaves, making them bigger to create the crop canopy we are familiar with. 

As a corn plant finishes creating vegetative parts, it starts to focus on creating reproductive parts that it will utilize later. In corn, we are specifically talking about the tassel and the ear shoots. Both structures are being created by a corn plant at V6. While there is only one tassel being created, there are multiple potential ear shoots on a corn plant. Each node of a corn plant has the potential to create an ear. Typically the primary ear forms around nodes 12-14. At V6, the plant is determining how many kernels rows its potential ears will have. The number of kernel rows on an ear directly effects yield and cannot be changed once it is determined. 

Lastly, the growing point of a corn plant comes above the soil surface at V6. Damage to the plant can be fatal if that damage happens below the growing point. 

Update on Frost Damaged Soybeans

Two weeks ago there was frost damage to some soybeans in the area. Last week's newsletter discussed some of my observations of the damage. You can find those observations at the following link: Herbers Seed Weekly Newsletter-June 4th, 2021

The image below shows a soybean plant 14 days after being damaged by frost. The red arrow denotes the damaged tissue from the frost. The green circles show the new growth that is coming from the axillary buds at the base of the cotyledons. 

Soybean New Growth

The Week Ahead

The 7 day forecast is trending towards warmer and drier than average conditions. If this holds true, it is likely we will be seeing more drought stress in the corn crop in the coming days. With the potential for heat and water stress in the corn crop, it will be interesting to see if there are any differences in the growth rate and the development rate of the corn crop. Next week's newsletter will discuss these topics and more.

About The Author

Andrew Blomme
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