Disease Observations

by | Aug 23, 2019 | Crop Watch

The better part of the summer and the growing season in the Midwest is over with. In many areas the struggles to get planted and nurse the crops are over with, but we are left with the aftermath. When traveling thru Iowa and surrounding states most of the cover crops that will be planted have been. That is the good news. The reason for the progress being made is that our monsoon season is being followed by a drought season. For the past four to six weeks most of the large rain fronts that were approaching the western edge of Iowa were either be blocked at the IA/NE border or forced either north to Minnesota or south into central Missouri.

The increase in grain prices were nice while they lasted, but disappeared as the USDA released acreage reports that seemed to fall into the ‘Fake News’ category. Somehow the human calculations or computer modeling don’t realize the impact of losing 19.2 million crop acres and having a major mid-summer drought which is reducing grain fill in corn and growth and pod fill in beans has on the overall production figures.

The smaller private crop tours already conducted have gotten a truer perspective on the status in each state and have not been afraid to use the term ‘disaster’ when they toured some of the eastern Corn Belt states. Then the biggest current factors are ‘will the crops receive enough GDUs to get the corn crop to maturity of black layer or will a normal or earlier than normal frost/freeze cut the season short’ and ‘will Iowa get their 2 to 4” rain before it is too late to help the crops?’ Then if the corn does black layer in the questionable areas will the weather be conducive for decent field drydown to the low 20s so the drying capacity of both the elevator’s and farmer’s systems are not overwhelmed.

Dry Conditions

In many parts of the Midwest the rain shut off one to two months ago. It is causing problems with both major crops. I checked a nearby field on Saturday and saw firing up to the ear. The ear was ¾ dented with extremely shallow kernels. Reports out of eastern Iowa, and much of Illinois and Indiana tell of a similar situation. The media is typically concerned about pollination but seems oblivious about the kernel abortion during the two to three weeks following if conditions are not friendly to the plants.

Another result of the dry soil is the lack of water to carry minerals into the plant to help fill the kernels/seed plus meet the physiological needs of the plants. The mass flow, diffusion and transpiration pull systems come to halt. The color of the plants in many fields plus root rots indicates the plants are hungry and thirsty.

Has anyone figured out what happened to the soybean plants this season? A high percentage of the fields were planted 4 to 6 weeks late. Many people noticed it took a long time for the plants in lots of fields to emerge. Then they seemed to stall out and produced little growth while the weeds kept growing. While June 21st is typically the date at which flowering occurs, there were many fields that delayed flowering until mid-July when the plants were as developed as the V6 to V8 growth stage. Now the terminal flowers are out and it is hard to find a decent terminal cluster of pods. Some of the flowering delay appeared to correlate with being burned with a PPT herbicide and accompanying MSO and AMS.

While getting a yield of 65+ Bu/A bean yield usually requires 17 to 19 podded nodes, the usual podded node count this year is down 25 to 35%. If the plants are going to compensate for this shortfall, where will it come from? I scouted beans last week that were all planted the first week in May and they are all carrying a third fewer podded nodes. Will the survey crews make note of this in their surveys?

One tactic high bean yield achievers use is to apply foliar mixtures of minerals during the R2 thru R4 growth stage to plump up the bean size. The method bypasses the extremely dry soils. Those mixtures typically include K, S, Mg and Moly. Applying them in a foliar mix is the most efficient way to achieve maximum results per $ spent.

Insects Seen

There were several insects of concern in Iowa soybean fields this season. I have seen very few fields where the aphid levels approached a treatable population of aphids. Their populations did not explode on the R4 leaves as normally happens. The super cold temps in S Dakota must have killed the eggs on the buckthorn

Drawing more attention were the Japanese Beetles and Thistle caterpillars. The former have mostly cycled out in central Iowa, but in areas are still defoliating tasty plants. The Beauvaria fungus applied now may offer the best control of the 2020 populations by infecting the soil dwelling larvae now feeding on grass roots.

The risk of another generation of thistle caterpillars was being mentioned but has not materialized. Gall midge larvae have been spotted in counties in western IA tunneling inside soybean stems. In states to the west and south the Dectes stem borers have been found doing the same thing. Lastly I did find a strange looking weevil on one SB leaf in NW Iowa. Was it an anomaly or a harbinger of a new threat?

Disease Observations

Stay observant of disease lesions on the leaves and stalks of both corn and beans. Normally the levels of infection decreases with drier conditions. The one corn disease that is much more common this season is Physoderma stalk and leaf blight. Its spores and their ability to infect hinge heavily on moisture films on the plants. The banding often seen on the leaves is the result of daylight being needed to infect.

Tar Spot, which was a very quick spreading and serious corn disease in 2018 and its wet conditions, has been very slow and late to appear this season. It was finally verified in Wisconsin fields during the last two weeks. The owners of those fields are paying close attention to any spread, knowing that it proved to be capable of subtracting 35 to 40 Bu/A of corn yield in a two-week time period.

CBD as a ‘Cash Crop’ Interest

The cannabis industry has been making news in many countries this year as many states now allow production and use of the CBD oils. During the WW2 era there was at least one industrial hemp plant operating in Kossuth County, Iowa. The regulatory framework is haphazard and has been tough to navigate, creating problems for major growers to get greenhouse plants delivered to their facilities. A number of farmers and investors in different states are anticipating getting involved in a crop that could offer a 3rd crop potential and a cash reward. The learning curve will be steep for many as having a pile of cash on hand does not guarantee success. There were a number of deep pocketed groups that put a hold on expansion when their early production plans didn’t go as expected.

What caught my interest was when I was visiting with a top Ag scientist said she was interested in using her new analytical instruments to identify the pain relieving oils. Her goal was to help her sister who had suffered severe damage to her arms in an auto accident 15 years ago. Her pain meds were now ineffective and she needed a product to get relief.

Simon Conway, WHO Radio host, interviewed an Israeli scientist two years ago. This guest related how the godfather of CBD oils, Raphael Mechoulam, PhD chemist at Hebrew University in Israel, made the statement that the cannabis oils could be used to successfully treat nearly every human ailment with great results and without the serious side effects seen with regular pharma, and much cheaper. He said they were a threat to the industry. He has written the $400 encyclopedia covering the oils. If you research the science the human Endocannaboid signaling/receptor system was discovered at the St Louis Univ. Medical School in 1988 using Govt funding. It was found to be the chief homeostasis system in the body helping to maintain steady internal levels when the environmental factors vary greatly.

Nasha Winters, who authored the book ‘The Metabolic Approach to Cancer’, is a Kansas farm girl and cancer survivor. She lectured at the Acres Conference in Louisville last year. Based on attendee requests she will be a guest speaker at the 2019 conference this December in St. Paul. She relates how the human body is greatly affected by the lunar and circadian rhythm cycles and how the endocanniboid system influences human health in beneficial ways.

Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143 or www.CentralIowaAg.com.