The days are becoming noticeably shorter and the crops are advancing in what has become a topsy turvy growing season. Everything seemed out-of-whack from the end of winter and the start of the planting season, to what we have in the field now. This was following the 2021 season with drought conditions during June and July with the August 10th derecho which was a size that most of us could not envision. As I mentioned in my last column the last four growing seasons followed pretty much the same script, where the bulk of mid-June thru mid-August are hot and dry with rain coming in scattered showers delivered at fast rates, often running off if infiltration rates are low.
The forecasted temps for our state and the Midwest for the Aug 19 – 26th time period are some of the highest in the last decades. Not quite dirty thirties category but enough that they could be etched in our memories. The biggest difference is that we now have air conditioning. The best house or building cooling systems they had in the earlier era were water coolers where 54-degree water vapor was driven by fans thru the dwelling. The net effect on our crops is that the combination of high temps, humidity, wind speed and amount of solar radiation determine PAN or PET, which are terms for potential or actual water use by the crop. Those terms are calculated and used in irrigation scheduling. If the water needs of the plant cannot be met by rainfall, dew or deep moisture reserves, the leaves can’t stay cool and the internal cell temps can increase to the point where cells die or their cellular components are denatured.
Big News of Last Week
The media headlines had to be the fires in Hawaii and on Maui. Myself and a few other individuals have done quite a bit of environmental toxicology on Kauai and Maui in recent years. Doing that during our winters provided a nice break. We worked with the locals and natives and learned that living there and coping with its challenges was not all roses. First of all, the natives never requested to become a U.S. state. What happened was the sugar cane company commandeered the land and water rights by occupying it and pushing the natives off land they thought was provided by God. They were ready to rebel and there was an uprising. The cane employees captured the queen, holding her hostage, and threatened to march her citizens off a cliff unless she signed the petition requesting statehood. Thus the U.S. based Alexander Baldwin sugar company gained control of 70,000 + acres of prime farmland on the island and the water that fell on it. Due to poor management, they shut down the cane business, but did not restore the water rights to the citizens or allow them to produce food crops so they could not become more food secure. If the boats delivering food quit coming they would be out of food in two days. As to the water, it is being sold to the resorts and hotels by the cane company rather than into the municipal water supply. The cane company was still using antiquated and wasteful open ditches and canals to move the water. This lack of water left the island and town of Lahaina handicapped in any attempt to upgrade their pumping systems if they ever had to fight a fire. Numerous fire fighters reported that no water was being supplied by the fire hydrants, leaving them powerless to fight the flames.
Denuding parts of the island has changed weather and rainfall patterns. During one trip we traveled to Lanai to visit with the natural resource field manager for Larry Ellison, the Oracle founder, who now owns the Island. On our return it was pointed out to us how many trees had been removed from the west coast of Maui and replaced by shallow rooted grasses, which turn brown quicker during dry periods. Rain gauge info has documented a serious decline in rainfall across this area in recent years due to the human alteration of the microclimate.
The Corn Crop
It has been a season with a dramatic difference in rainfall amounts in all section of the state. It was predicted by Dr. Atkins that western IA was going to receive decent amounts of rain vs Eastern Iowa and points east. That turned out to be correct for May and June. Beginning in late June parts of SE IA and NE Missouri began to get lots of rain. Much of Northern Iowa has been getting rain, but in small increments and just at the last minute. Except for central and west central parts of IA there has been no deep moisture reserve, meaning this coming week’s intense heat could influence final yields in a big way. The corn crop has been walking along cliff most of the season.
Early preplanning for dry conditions by the way of paying attention to rooting architecture and rooting depth of genetic families to maximize soil moisture extraction potential, the use of mycorrhizal seed inoculants, having adequate zinc levels, soil ground covers and improving soil health to improve water infiltration rates will all be critical. Another area which several very knowledgeable soil chemists and practitioners are studying is the late season decline in plant health of the corn crop. We know that bacterial diseases cause their damage by plugging the plants’ vascular system. Might certain minerals, specifically iron, or iron and manganese, when occurring at very high rates, add to this plugging, especially in a season with wide swings in soil temps and moisture. Now a plant disease specialist may not be able to detect this, but a mineral analysis of the plugged root tissue would. One of the chemists involved is suggesting foliar applied copper may be the answer to this problem. This decline began to become noticed by early August and very noticeable by Aug 15th. What is most observable is plants turning brown from the ground up and tassel downward with the middles of the plants staying green.
So how accurate will the guesstimates made by the crop survey teams which will be held in the major corn states in the near future? They make their estimates and guesses based on what has happened the following weeks during normal seasons in the past. Nothing is normal anymore. A major percentage of the corn crop was planted later than normal, so weather conditions during the last half of Aug and Sept could influence final yields more than normal. The projected early and mid-Sept cold air inclusions could do the same. At this point I see a wide range in ear size. This hot week will speed crop development along faster than normal, resulting in shallower kernel depth.
The SB Crop
Luckily the rains arrived in time to facilitate the pods finally filling decently. There were pods aborted in the fields where the leaves were flipping over due to moisture stress. And like normal the morning fogs when normally begin appearing starting in early August did as forecast. This allowed a few of the normal leaf disease such as Downey Mildew showing up as small irregular yellowish spots with translucent hairs on the underside of the leaves. Luckily these don’t affect yield much. The Septoria fungus causes yellowing of the lower leaves, followed by dropping off the plants. There are fields where the yellowing from SDS is now very noticeable. Bob Kremer’s work in his USDA ARS position at the Univ of MO documented this this is due to the slaughter of the Pseudomonas fl bacterial population by a systemic herbicide.
With more SB growers improving their knowledge base concerning high SB yield management, it was possible and fun to see how much late season (R1, R3 and even to R5.5 or R6) applications of minerals has contributed to pod retention and fill. The guys who have worked with livestock grasp the concept readily when you liken it to feeding cattle or hogs regularly when they get hungry. Plants get hungry in the same fashion. Part of the trick is learning which minerals should be used to optimize pod fill. This is still a point of discussion in both Americas.
Corn Rootworm Situation
More rootworm larvae feeding and the lodging that can come with it has appeared in many parts of the state. There are a number of causes: early microbial degradation of planting time insecticides; mutations by the GI tract microbes allowing adult beetles to use soybean leaves as a food source; extended diapause of the NCRW species; proof of the existence of a non-recessive gene in inheritance in at least some insect species; lack of production of the delta-endotoxin based protein in droughty or stress conditions and knowledge that in-plant toxin production amount varies by variety. What this all means is that nature allows insect biology and the microbes that live in or around insects to be fluid and highly adaptable. The most effective control will be something that works within nature that will focus on an inherent insect weakness.
This lodging that occurred with root feeding, then winds of any strength, tipped plants over to reduce ear size and make harvest more difficult. A newer company called Meristem has a biological product which was tested N of Mankato years ago which was shown to help the plants form more recovery roots. It was placed in a number of plots in the Midwest. In addition, there are several other products which have proven to reduce larval feeding awaiting EPA approval. The most interesting one to me is a fungal product which when named, only a mycology student would recognize.
Where lodging occurred due to strong winds or root feeding, any late season applications of pesticides or minerals to aid in grain fill was only possible by aerial applications. This equipment has now been bolstered by the addition of drone and teams of operators trained and licensed. These will offer a service by licensed operators willing to do jobs that ground machines might not be able to do, or planes already have converted to dry applications.
As a tidbit for interested fruit growers, the IA peach crop was the best in years.
Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143 or www.CentralIowaAg.com.