Herbicide drift, fungicide decisions, and iron deficiency chlorosis were common questions or issues received and/or observed by ISU Extension and Outreach field agronomists this past week. Read on to see what's happening in different regions across the state.
North Central Iowa
Angie Rieck-Hinz (Region 3): “Parts of my area received some much-needed rain in the past 10 days and other areas received very little. Rainfall reports from June 27 through July 6 show Iowa Falls received 0.23 inches, Fort Dodge received 1.14 inches, and Northwood received 2.44 inches. The table below shows rainfall for selected stations across NC Iowa from April 1 through July 6 (please ignore the amounts reported for Humboldt). Beans are R2 (full flower), and I have seen the beginnings of a few pods in some fields. Iron deficiency chlorosis (IDC) is still showing in fields on high pH soils. Late last week I noticed some of those areas were also starting to wilt and exhibiting dying plants. On closer inspection this week it appears to be Phytophthora root and stem rot (see photo below). It seems odd to be seeing this now, but these areas had recent rainfall with amounts over an inch. I have not found any soybean aphids or soybean gall midge in the soybean fields I have visited, but I have seen some minor Japanese beetle feeding. Off-target movement of herbicides continue to be the most frequent phone calls I receive. Corn is V16 to VT. I have seen no leaf diseases, but I have had many questions about the use fungicides. Alison Robertson summarized her thoughts on the use fungicides in dry (drought) conditions in this article Can a fungicide benefit drought-stressed corn?"
Josh Michel (Region 5): “Some parts of NE Iowa were lucky to receive some much-needed rainfall last week. Up to 0.5 inches fell in parts of Dubuque, Fayette and Clayton counties. While up to 3 inches of isolated rainfall fell in Allamakee County. Corn is generally around V10 and continues to grow very quickly. Soybeans are generally around R1 to R2. Alfalfa second crop harvest is well under way, with yields being reported as “better than expected”, considering the lack of rainfall for most of the month of June. Oats continue to look good. Most fields are headed out, with around 40% turning color. Recent rains have also helped provide some relief to pastures, but warming temperatures continue to slow down the growth of most grasses. Recent field calls and questions have centered on managing alfalfa and oats as well as handling several calls pertaining to pesticide drift complaints.”
Aaron Saeugling (Region 10): “Despite poor subsoil moisture conditions, corn and soybeans look remarkably good. Pastures are declining and reports of wells going dry are becoming more common. Corn is in the late vegetative stages and a few tassels are peeking out. Most soybeans are now shading the rows and have exploded with the rainfall in those areas where rain was received. Overall things look to be in good shape at this point, but we will see how long we can go if the dry conditions persist.”
Meaghan Anderson (Region 7): “Most of central Iowa missed any rain again this week, with the big exception of a large pop-up storm in NW Dallas County last week that dropped a significant amount of rain there. Our totals since April are running somewhere between a 4- and 8-inch deficit compared to historic averages. Considering the situation, crops look really good. Most corn is in late vegetative stages and many fields will be tasseling by the end of this week or early next week. With tasseling on the horizon, many are weighing whether to make a fungicide application this year with the dry conditions. Most soybeans are in the R2 stage. Phone calls in the last week have continued to be primarily about soybeans, including questions about herbicide drift, carryover, iron deficiency chlorosis (IDC), and wilting."
East Central, Southeast, and South Central Iowa
Rebecca Vittetoe (Region 8): “Rainfall across EC Iowa this past week ranged from about 0.1 to closer to 1.0 inch in some areas. Corn is in the late vegetative stages across EC Iowa. I’ve spotted tassels starting to peak out in a few fields, and by the end of this week and early next week many fields will be tasseling. Soybeans are mainly at the R2 stage. Overall, the corn and soybeans are looking pretty good. I have seen basically no disease pressure in corn or soybean fields and can also find some minor Japanese beetle feeding in soybean fields. Questions this last week have involved managing hail-damaged crops, fungicide applications, herbicide drift in soybeans, potassium deficiency symptoms, and iron deficiency chlorosis (IDC) in soybeans. While IDC is not common in this part of state, I have seen it in a few soybean fields near or closer to gravel roads where the soil pH is higher. With most POST herbicide applications having wrapped up, other field activities this past week include starting harvest for the second hay cutting as well as harvest for small grains like wheat and cereal rye.”
Virgil Schmitt (Region 9): “ Rainfall during the week of June 28 to July 4 in the counties I cover, was generally 1 to 3 inches south of Highway 92 and then fading away going north, with northeastern Clinton County and eastern Jackson County receiving less than 0.10 inch. In general, temperatures during the week of June 28 to July 4 in the counties I cover were near normal. Corn is generally V14, +/- one leaf collar. A few fields started to display tassels toward the end of this last week. Soybeans are generally about R2. The second cutting of hay began last week and was mostly completed by Sunday, July 4. Cereal rye harvest began last week and continues. Some oats fields are starting to turn color. Calls and farm visits last week mostly involved herbicide drift.”
Clarabell Knapp (Region 11): “The area has experienced more warm and drier weather than previous weeks. There were some rain showers that came through this area, and weekly rainfall totals ranged from a couple tenths of an inch to 1.0 inch. Many soybean fields are reaching R2, and early planted corn fields are close to tasseling. Fungicide applications have been and are continuing to be applied. Wheat fields are have begun being harvested in the area and yields have been good. Pasture and hay field regrowth has been doing well, and many hay fields are being cut and baled. Field calls have been focused on corn and soybean disease pressure, herbicide applications, and weed control.”
Check out the map below to find your local ISU Extension field agronomist and find their contact information here!