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The Cropwalker - Volume 3 Issue 29

Always read and follow label directions.

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Crop Conditions

Weather - Rainfall continues to be scattered. Areas that received rainfall this past week will have great corn potential and possible white mould in beans. Wheat harvest has pretty bunch wrapped up with some areas with later plantings still working away. Harvest is at a standstill in areas that haven’t been able to finish due to the rains over the weekend Cover crop seeding are in full scale. Soybeans still some new flowers. White mould will be starting to show in some fields. For many SOYBEAN fields, it is too late to spray for mould. White mould will infect and start to grow 10-14 days BEFORE you see any white mycelium.  Have been hearing of bean leaf beetle feeding in soybeans, see article below on thresholds at various stages. Corn has finished pollinating. Western Bean Cutworm (WBC) numbers are falling. In traditional areas scout for egg masses. You have to talk to your crop protection supplier to find out what is going on in your area. High adult count does not mean high egg mass numbers.  –. Spring grain harvest is ongoing. Some issues with lodging. Yields have been respectable where grain was planted early and received rains. Forages third cut is or will be starting. Potato leaf hopper numbers are falling. If you have stunted alfalfa in flower consider cutting/clipping to get another cut. It will not regrow unless you get rid of the current top growth. Probably no benefit to spray for leaf hoppers now. If you are trying to inter seed grass into a thin stand now is when you do it. Annual rye grass can give you some growth this fall and also next spring. Edible beans issue is do you spray for WBC. There really is no good answer since you can’t scout for them until there is damage.. Check with dealer where you will deliver the beans. Probably a good strategy is, if the WBC traps in your area indicate a lot of WBC moths spray to control WBC in edibles. Products such as Coragen, Delegate or Voliam Xpress offer residual activity on WBC.  Starting to see some colour change in early beans. Consider 2nd or possibly a third pass of fungicide if beans are still in flower.

Thoughts from R.L. (Bob) Nielsen Agronomy Dept., Purdue Univ. A plethora (meaning a whole lot) of blank cob tips can quickly ruin the joy of walking a cornfield in the middle of August. Before getting too bent out of shape over the missing kernels, remember to count the number of harvestable kernels on those ears. Sometimes, ears exhibit 1 to 2 inches of blank tips; yet still contain 16 rows by 30 to 35 harvestable kernels per row. Those are perfectly acceptable ear sizes in a year where dry weather has been a concern.

Later this week we will be forwarding a separate email on winter wheat varieties selection for fall 2020.


Things to do this week

“The most important thing you put into your field are your eyes” Adam Garniss CCA ON Huron County

  1. Check soybean fields for spider mites, any diseases, weeds that will need a preharvest burn down. Take pictures of diseases.
  2. Record where all manure went this year. And get a manure sample.
  3. Talk to your seed dealer about wheat seed.
  4. Check over drill, replace blades on drill if they need it. (biggest issue I see with wheat stands is poor drill maintenance and setup, then wrong seeding rate).
  5. Check forage fields to decide what fields will be turned under this year.
  6. If not done yet, make arrangements for soil sampling.

South West Diagnostic Days

The day was held and now you can watch a replay of the day’s events.

Horst Bohner OMAFRA gave a convincing talk along with field numbers that showed you should plant soybeans at 1.5” every year all the time, within reason. Maybe a bit deeper on lighter soils.

Dr Dave Hooker on planting dates for corn. Stated that you should be more concerned about losing yield on your last planted acres as opposed to losing yields on first planting. He also stated that if you have heavy soils it is better to plant them early as opposed to late if the soil is fit. My experience backs this up. If you have heavy soils and they are fit in April the soil will be in better shape than in mid-May after it receives a lot of pounding rains that destroy soil structure.

Albert Tenuta ran through the main soybean diseases this year. They are; 1) phytophthora root rot (purple lesions from soil level up to 1st or second node. Leaves may stay hanging on the plant)  which is controlled with genetics and seed treatments. 2) The next is fusarium wilt root rot which there is no known genetic resistance. When you cut the plant open you will see a brown rot in the centre part of the plant. The other main disease Albert talked about was Sudden Death Syndrome. It is a fusarium fungus that has a root component and leaf component. After flowering the leaves how scattered spots between leaf veins. It can look similar to Brown Stem Rot. The latter has a brown colour of the pith which is the middle part of the stem.

Tracy Baute OMAFRA talked about the many natural predators that control insects. She mentioned that you should be sure you have threshold levels of insects before you spray since most insecticides will also control beneficial insects.

Post Harvest Wheat - Weed Control

You pick your herbicides based on weed type. For most annual weeds use low rate of glyphosate. If you have fleabane consider using Enlist DUO (2,4-D Choline, as amine does not mix well with most glyphosate formulas) or MCPA Amine 600 (mixability maybe an issue); Enlist will perform better than MCPA Amine on fleabane. If you have perennial weeds such as perennial sow thistle, Canada Thistle, milkweed, bindweed you cannot control them now. Have to wait until mid-late September to control these. If you use 2,4-D or MCPA there is a delay before planting most cover crops. Tillage may be an option to control annual weeds, broadcast fertilizer or manure before you work the ground then seed cover crop. Then control any perennials before freeze up in the fall. We do not recommend the use of Ester formulations at this time of year due to crop injury.

Handling Red Clover for Plough Down

There is no herbicide that you can spray on the clover that will not affect the clover. If you have annual weeds wait a couple of weeks after you harvest the wheat and clip the field. This removes enough of the weeds that generally allows the clover to grow back faster than the weeds. I read where it is suggested you use MCPA Ester to control weeds in red clover for plough down. DO NOT DO THIS. Ester formulations are very volatile. They can very easily volatilize and damage another crop. You should not be spraying esters from soybean emergence until soybeans turn colour.

Nutrient Removal with Oats after Wheat – Expect to harvest at least one tonne per acre of dry matter by seeding oats now. You must apply at least 40 pounds/acre nitrogen to get these yields. This amount of dry matter can remove about 10-15 pounds/acre of phosphorous and 40-50 pounds/acre of “K”. You would need about 2,000 gallons per acre of liquid cattle manure to replace these nutrients. If trading with a cash cropper then applying 3,000 gallons/acre and be able to harvest the oatlage would be a reasonable trade.

Oats vs Oats pea mixtures

Very little data. Most recent Ontario data is 1999. What indicates is that oats at boot stage could have 15% protein while oats plus peas could have 19% protein. As you allow oats to get to dough stage protein drops and yield goes up. The actual yield and % protein of your mix will depend on harvest stage. Later harvest lower protein and higher yield. Research from South Dakota State University suggests the same type of trend.

Full report at:


Tar spot on corn. Below is an image taken from University of Indiana web site. Tar spot is the new corn leaf disease. First identified in 2015 in the mid-west. It is moving from there and will probably show up in Ontario this year. If it comes in early, tar spot can cause a 25% yield reduction. There are many things that look like tar spot in the corn field. This disease will not wipe off the leaf. If you turn the leaf over you can see how it is growing into the leaf. There are no known resistant hybrids but there will probably be a difference among hybrids. When checking corn fields keep an eye out for this. It will probably be in mid to upper parts of the corn canopy. It is felt that many fungicides will have activity on tar spot, a quick look at the Crop Protection Network suggests that there are quite a few mixes, some of which you may already be using, that offer some level of activity. In 2018, tar spot was also listed as the number 2 leaf disease for yield loss.

Picture 1 - Tar Spot in Corn

Defoliation and Disease Severity Training

The crop protection network has a number of training exercises available on their website.

The one that interested me the most is for estimating defoliation for soybeans is available at: https://severity.cropprotectionnetwork.org/crop/soybeans/soybean-insect-defoliation-training

At the end of the training they provide an accuracy of your estimates relative to what they feel is the right answer.

For soybeans diseases, the Crop Protection Network also has a training module on estimating the impact of leaf diseases, you can find this module at; https://severity.cropprotectionnetwork.org/crop/soybeans/general-soybean-disease-severity-training

Lastly, there are a few for corn as well, one that piqued my interest was the ear rot severity training model. You can practice your estimates at; https://severity.cropprotectionnetwork.org/crop/ear-rot/ear-rot-severity-training

A list of all training models around severity is available at; https://severity.cropprotectionnetwork.org/

Bean Leaf Beetle Thresholds

Unless you are growing seed or non-gmo food-grade beans, you are unlikely to have to spray for bean leaf beetle. Watch that you are within the pre-harvest label of the product you choose to use. The thresholds for bean leaf beetle feeding are;

Figure 1 - Soybean Defoliation Chart
Picture 2 - Bean Leaf Beetle Feeding in Soybeans

Soybean Insects and Product Selection

If you are spraying for spider mites, you have one product option, that is dimethoate (Cygon/Lagon). If you are spraying for aphids or bean leaf beetles, you might not be using Lagon, but if you have Spider mites in the field, you should be using dimethoate. Check the product label when selecting an insecticide to ensure you are not chasing one insect, but allowing another to take over the field, resulting in another trip over the field. At this point I doubt most areas will have to content with aphids, if you do, we are getting late enough that many of the fields maybe at R5. You will not require a product with residual in most situations at this stage to knock down aphids and keep them in check.

Spraying for Spider Mites

If you had spider mites at threshold in soybeans or edible beans prior to this weekend’s rain events, experience would suggest you still need to spray. The mites are far enough along and already causing enough damage the natural predators will not keep them in-check. I have found that if they are trace or light levels, and you do not have any hot spots, the plants are usually healthy enough after a rain event plus natural predators that provide a situation with minimal yield loss. You can spray headlands to control them, in this situation you will have to be on your scouting A game and spray prior to reaching crop thresholds. Typically once the boundaries have reached crop thresholds, you will have mites within the field and have to spray the entire field.

White Mould

On Friday I found my first field with white mould. To estimate yield loss for plants that have white mould count 50 or 100 plants, make note of how many have white mould. The percentage of plants that have white mould is your percentage yield loss. At this point in the growing season any plants with white mould will be essentially a 100% yield loss, as the neighboring plants will not be able to make up for the difference, it is too late to adjust.

Picture 3 - Above canopy symptoms of White Mould
Picture 4 - Below canopy symptoms of White Mould
Picture 4 - White Mould on Stem

Timing of Corn DON and Vomitoxin Reduction

Dr. Dave Hooker had posted this chart several weeks ago on Twitter. If you are thinking of applying a DON suppressing fungicide in corn (Caramba, Miravis Neo, or Proline) the optimal staging for DON reduction is silking to day +3, with some control at day +5. At day +11, it was equal to the untreated check.

Safe Rates for Fall Strip Till

As far as I know there are no rate limitations when applying fall MAP or Muriate of Potash in strips. Machine capacity, soil test/soil type, and $$$ are likely to determine the maximum rate to be applied, rather than spring corn seedling safety.

"Where I come from rain is a good thing."

- Luke Bryan