AGRONOMIC UPDATE: July 31, 2024….Quick trip into the furnace…and maybe back out again….

Topics:

– Growing Degree Day Update

– What’s going on in my fields?…..Corn Development, ET rates, Disease, etc.

– Insect Update

– Soybean Development

TEMPERATURES & GDU ACCUMULATION:

As of July 30th, we have accumulated approximately the following for Growing Degree Units in 2024:

Planting Date GDD’s2024 Average GDD Departure from average

April 23 1800 1779 + 21 (+ 1 day)

May 4 1722 1697 +25 (+1 days)

May 14 1517 1606 +11 (even)

From the above numbers, we see that we have gained just a little from last update….overall crop is still moving along at an average pace. Even the mid-May planting dates are average. We are currently 3 days behind 2023. Still need 800-900 GDU’s to finish the crop, so we still need some heat into August and September….

The above map is the departure from normal temperature for July 2024. We continue to trend 1-2 degrees below normal. Temperatures are forecasted to stay hot into mid-next week, but it looks like a significant cool down is coming end of next-week….more typical of what we experienced in June for temps. This will give us a break from the heat, but will keep us needing most of September for good fill. It will also lead to increased disease outbreaks…more on this below.

WHAT’S GOING ON IN MY FIELD?…..Corn Development, Disease, Crop Water Use..

Most of the corn crop is in the late-R2 (Blister Kernel) to early-R3 (Milk) to R3 (Milk) stage. The heat last week really pushed the crop along. The late planted fields (ie. after rye, etc.), are just starting to tassel.

Pollination overall seems to be good so far. Finding the usual checkerboard pattern on the butt of the ear in some fields, but overall looks good. Some fields had delayed pollination, so we are seeing some unevenness in pollinated kernels in some cases. This was due to the cooler temps and dewy conditions during pollination, along with very little wind to help move pollen around.
Plant height this year seems to be normal overall. Seeing shorter corn in the sand on the first-planted fields.
At R1, potassium uptake is essentially complete, and nitrogen and phosphorous uptake are rapid. Last round of N should be on, or going on shortly.
Blister Kernel occurs approx. 10-14 days after Silking. Starch has begun to accumulate in the watery endosperm and the kernels are beginning a period of rapid, steady, dry matter accumulation that will continue until physiological maturity in approx. 50-60 days after silking.
At Blister Kernel, maximum ear length is achieved. Although not as severe as at Silking, stress over the next two weeks can still have a profound effect on yield through kernel abortion, which is why this last rain was such a Godsend….
Kernel abortion from stress can occur through the Milk stage(18-22 days after silking), however when the plant reaches Dough, kernel abortion will no longer take place, and any yield reduction from then on out will be from lower test weight. We are currently in the ‘tip-back’ stage of growth. This stage will last over the next two weeks or so. Temperature and sunlight will play a role here….
As far as sunlight is concerned, we are currently running about 10% percent below normal over the last month. Sunlight, of course, is now a much bigger yield factor, since we are now beginning the crucial grain fill period. As such, how much sunlight and when it occurs during the grain-fill period, will play a role in overall yield and late-season plant health. Lack of sunlight early in the grain fill period (i.e. right now) can increase potential for the ear to tip back. Extra stress will occur if sunlight is reduced and temps (especially nighttime) are higher than average (which is not predicted). This stress occurs because, since temps are high (especially nighttime temps), the energy demand on the plant is higher than average; couple this with reduced photosynthesis, and this leads to greater energy in the plant just going to maintain itself and not to filling the ear. It is an axiom in corn production that when you have to run your air conditioner at night, it is not good corn growing weather. The forecasted cooler temps next week, will give the crop a nice break.
Relative Humidity over the past month has been 8-10% above normal, with a daily average RH in the low-to-mid 70’s%. While this leads to decreased ET rates; it increases the potential for more disease in corn and soybeans. The two graphs below show daily maximum RH for Jan-Jul. Frist graph is 2023 and second graph is 2024 up to July 31st. Main thing to note is the comparison of the time period July-August between the two years. 2024 looks to be even more humid than 2023….and 2023 was a very humid period from July to mid-August. We continue to have a disease breeding environment….
ET rates for the past 15 days have been averaging .27 inch/day, which is normal. The forecasted cooler temps next week will keep overall ET rates normal to slightly below normal….keep in mind corn at Blister Kernel is average of .28/inch per day and Milk stage is .25″/day in normal weather….we are closer to .30+/day when hot & windy. Last Friday/Saturday were tough ET days, as one can see from this daily maximum RH graph. Just look at the far right and notice the drop in humidity. That, coupled with winds, led to high ET rates….
Soybeans are now at peak usage at R3-R4 stage….over .30 inch/day normal. Maintaining an adequate soil moisture profile will be key over the next three weeks or so. As you think about irrigation needs over the next two weeks, keep temperatures and relative humidity in mind as we move forward to see what actually occurs to help reduce potential water stress or potential over watering. If dew points are low (dry mornings), that means relative humidity is low, and ET rates will stay up higher than normal. On the flip side, if heat indices are high in which a 95 degree actual temperature feels like 110 degrees (which is what we experienced for most of the last 10 days), then relative humidity is high and ET rates will be average to below average. Forecasts for the next few days week are calling for hot temperatures and higher humidity….
So far corn leaf diseases continue to be on the low side, however, we are seeing first signs of Southern Rust lesions in some area fields.
This disease can ‘blow up’ quickly, so highly recommended to watch your fields for outbreaks….better yet, recommended to apply a fungicide to halt the disease. One does not need a lot of residual now, and there are some ‘lower priced’ products – less than $7/A for the product…well worth it if southern rust explodes! Otherwise, seeing mainly Bacterial Leaf Streak, and Grey Leaf Spot is increasing, and we have seen a few Northern Corn Leaf Blight lesions around. Have yet to see Tar Spot in the area, but it has been confirmed in the counties to the east and south of us.
Fungicide application should be on, or going on now, and into next week on the later planted fields. You want to protect the plant when it is working the hardest, which is silking through milk stage (which is NOW!). Reminder, a fungicide will not help control Goss’s Wilt or Bacterial leaf streak.

SOYBEAN UPDATE

Much of the crop is in the late-R3(pod set) to R4(full pod) stage of growth. This is normal in my opinion. The heat has also pushed the soybeans along as well. Overall plant height will be tall…the beans have really taken off as of late. Keep this in mind when irrigating….
Peak water use, nutrient demand, and overall energy demand in the plant occurs at R3 and into R4 stage….i.e. right now and into the next few weeks!
ET rates in soybeans reach peak at R3 into R4 stage (.30+ in/day) and will continue to stay high through R6(full seed). See comments above on corn ET rates, as the same applies for soybeans. One will need to be careful not to water constantly to help reduce disease potential (see below on white mold) due to a constantly ‘wet canopy’. If White Mold becomes a problem, it will be best to water at night and leave off during the day so the canopy has some chance to dry out. In heavy soils, when irrigation is needed, we recommend running a heavy irrigation amount (.80 to inch+) and then leaving it sit for a while.
We are seeing first signs of White Mold in a few area fields. Weather conditions of the past few weeks have been conducive for development of this disease. Too early to tell yet, but if the above forecasts hold true, expect to see higher amounts of white mold begin to show up. Any 2^nd treatments for White Mold need to go on at R3 and should really be on by now. See the attached link for White Mold management. Managing White Mold in Soybeans We recommend Aproach, Viatude, or Delaro fungicide for any white mold control. High temps and dry mornings will slow the disease down.
Sudden Death Syndrome – so far not seeing much for SDS in area fields. We would expect to see more of this show up as the weeks progress.

INSECT UPDATE – Corn & Soybeans

Overall it has been a ‘quiet’ insect year in both corn and soybeans. Much of this can be attributed to the wet conditions experienced this spring.
Seeing historically low levels of Corn Rootworm adults. This is due to the wet spring, I feel. Compared to prior number of years, seeing very low numbers. We don’t expect to see numbers increase much over the next few weeks, as the heat of the past 10-14 days should’ve ‘pushed’ them out. However, keep an eye on them through August, in case an odd field shows up that needs treating for next year….if a treatment has not already happened.
Western Bean Cutworm numbers are historically low this year. They can be found in sandy fields, but overall infestation levels are low versus what we have seen in prior years. Any treatments now will be strictly rescue…
We are just starting to see the first 2nd brood ECB moths start to fly. Keep this insect in mind on your conventional and popcorn acres over the next two weeks.
Overall insect pressure in soybeans has been very light. Very little defoliation going on yet. Begin scouting for Bean Leaf Beetles as they will begin feeding on developing pods over the next few weeks. So far we are not finding any Soybean Aphids. If you have made an insecticide application already, or are going to, this should give you season long control unless a severe outbreak of one of these insects occurs.
Dectes Stem Borer – be on the lookout for this insect starting now and into harvest. We have seen the adult beetles in some area fields over the past few weeks, actually pretty heavy amounts of adults as well. Watch field edges first and let us know if you are seeing wilted and dying plants as they move in from the grassy edges. If you see this, keep these fields in mind for earlier harvest. Dectes Stem Borer in Soybeans
Seeing a few small colonies of Corn Leaf Aphids(dark green aphid) in area corn fields. They tend to proliferate under cooler and damper conditions, so we may see their numbers increase in the area. They are not an economic concern, but you may begin to notice them as you walk through your fields.
So far not seeing much for Spider Mite colonies. However, if temperatures turn out as forecasted (cooler temps and higher relative humidity), infestation levels should be on the light side. Keep an eye out for this insect over the next month or so.

Please mark your calendar for the Pioneer Annual Customer Appreciation Supper which is set for Friday, August 23th. Invite will be coming out soon! The Pioneer Plot Tour is tentatively sent for, Wednesday, September 4th.

Please contact us with any questions or comments you may have! Thank you for your business!!

Starman Seed Service, Inc.