Agronomist Notes

Crops are finally starting to show signs of maturing as we move to mid-August. I’ve been busy timing some pre-harvest fields that were seeded mid-April and sweeping for insects. The aerial applicators seem to busy but I don’t have any clients nearing threshold yet for lygus bugs in canola.

With another ½ inch of rain last week many double seeded areas, water runs and manured fields have begun to lodge. Thankfully the forecast is calling for temperatures in the mid-twenties and only a few scattered showers this week. It looks like the last week of August or the first week of September will be very busy with canola swathing beginning the same time as barley and early-seeded wheat will be ready. Winter wheat harvest is less than a week away with peas following shortly after.

This week we’ll briefly discuss lygus bug thresholds and my theory on pushing them higher. Next, I’ll give you an update on the canola seeded on 24-inch versus 12-inch rows. We’ll look at the decision process to decide whether to straight cut canola or not and also how to estimate the yield loss from sclerotinia in canola. Last, I’ve provided you with a list of pre-harvest intervals for fungicides to avoid going over any maximum residue limits. We’ll finish with fundamental and technical grain market news.

Agronomy

Bump up your lygus bug threshold

For the last four years I’ve doubled the lygus bug threshold I use from 2 to 3 per sweep to 4 to 6 per sweep. Conscious that we’re giving up some yield, I’ve done it to help build up the level of beneficial insects. I’d rather let the predators of lygus bugs do the work instead of relying on insecticide each year. I’m happy to say the plan is working really well!

I have a few clients who used to spray almost every year for lygus bugs but no longer have to. It wasn’t uncommon to find 5 to 8 lygus bugs per sweep. Now, we rarely find anything over 1 per sweep. The neighbors are finding 8 to 10 per sweep this year and are wondering what gives. First, we do everything we can not to stress the crop, from managing residue properly to good fertility, accurate seeding depth and plant stand densities. We try to do all the little things right which helps build a big, healthy crop that is unattractive to insects and we push the threshold to double the industry average.

So, if you too are doing all the little things right, take the next step and bump your lygus bug thresholds to 4 to 6 per sweep. Within a few years you should start seeing a reduction lygus bug numbers and begin reducing your dependence on insecticide. Go spend that $12.00 an acre you saved on insecticide on a nice new swather with an 82-inch opening. That’s what my clients are doing. SL

Update on canola seeded on 24-inch rows

In a previous issue of Beyond Agonomy News, I featured producer Justin Nanninga from Barrhead who planted Nexera canola on 24-inch rows using his JD Conservapak. Now that we’re nearing the end of the season, here’s an update on his progress. The following observations were made by Peter Gamache from Controlled Traffic Farming Alberta who visited with Justin last week.

Across the 160 acre field Justin planted 80 foot strips (two passes up and back with the 40 ft drill) alternating 12-inch and 24-inch rows. He planted all the 24-inch rows first and then went back and seeded the 12-inch rows thanks to an accurate GPS. The variety was Nexera seeded at 4 lbs/ac on both the 12 and 24-inch rows. Justin did have to go back and spot spray some wild oats earlier in the year. The field is in variable rate and fungicide was applied at early flower. The previous crop was peas that yielded 50 bushels an acre.
 
The observations of the crop which has finished flowering were:

• No visible maturity difference between the 12 and 24-inch rows
• Stems seem to be thinner in the 24-inch rows
• Plant counts were about the same, 12 per foot of row
• Weeds not a problem in either
• Pod counts on main stem the same for both

I was pleased to see there was no difference in maturity as many people have speculated that the crop would take longer to mature on wider row spacings. I think we can lay that theory to rest now.

Also, I find it interesting to see that plants per foot of row were the same. The stems may be marginally smaller but perhaps the seeding rate is too high in both row spacings. Perhaps Justin has hit the wall with the number of plants he can pack into one row. Backing off the seeding rate by another pound or two would allow him to maintain optimum yield and maturity with just 6 to 8 plants per foot. The industry standard for canola plant stand densities are 8 to 12 plants/ft2 but then there is nothing standard about what Justin is doing with a precision drill on wide row spacings! Besides, I like the thought of saving $8 to $16 acre in seed costs while maintaining or increasing yield. 

This harvest, Justin and his consultant Colin Bergstrom plan to take yield measurements from 6 to 8 strips across the field. Justin’s swather is equipped with GPS guided autosteer so he should have two full 30-foot swaths in each test strip. What a great way to run a true comparison with measurable results. Thanks Justin and we look forward to hearing the results this fall. Good luck! SL

To straight cut or swath, that is the question.

With so many "vertically challenged" canola fields out there, some producers are cringing at the thought of cutting their canola short and leaving very little stubble to anchor the swaths. The obvious question then is, do I leave it to straight cut?

Here's a checklist I've adapted from the Canola Council of Canada to help you make the decision to straight cut canola:

Time of year - You should be making the decision whether to swath or straight cut within the first two weeks of August. If the crop maturity has you asking this question in the last two weeks of August, the risk of the crop maturing under cooler August-September weather may be too high. Cooler nights and shorter days can really slow down crop maturity and push your harvest window out to mid-October or later.

Crop canopy - The crop should be well knitted and slightly lodged to reduce the chance of pod shelling and pod drop. Remember that pod integrity can be affected by frost, drought and weathering caused by dry/wet conditions.

Uniform maturity - The crop should be relatively uniform to ensure over-ripe areas do not weather and shell before the rest of the crop is ready to harvest.

Disease - The crop should be relatively free from diseases including blackleg, fusarium wilt, sclerotinia and alternaria. These diseases can cause premature ripening, which can in turn cause pod shattering.

Hail - Crops affected by hail are poor candidates for straight cutting due to the probability of greater disease infection through damaged tissue and reduced pod integrity from physical damage. Also, any late season hail often causes greater levels of damage to standing crops than swathed crops.

Number of acres - Straight combining can be a finicky process because the canola stems and pods can still be green and tough even though the grain is dry. This can slow down harvest efficiencies significantly, bringing you down to 3 mph in some cases. If you have a large number of acres to cover, and you seeded those acres in a short time span, I would suggest allocating only a portion to straight cutting. SL

To learn more about straight combining, go to the http://www.canola-council.org/contents11.aspx

Reference: Canola Council of Canada

Estimating sclerotinia damage – Should we have sprayed a fungicide?

We are coming into the stage where canola fields should start showing signs of pre-maturely ripened heads caused by sclerotinia.
Diseases like sclerotinia stand out like a sore thumb this time of year but how do you know if a fungicide would have paid off? Let’s do the math on how to determine whether we should have sprayed a fungicide or not. For this example, we’ll assume the infected plants contribute nothing to yield. In reality, infected plants have decent seed size this year but may be lost due to shattering.

The typical sclerotinia yield loss equation is: Yield loss bu/ac = % infection × 50% × expected yield.

Steve’s quick math

I’ll spell out the process I use to put a dollar figure to the loss and then do an example.

1. Start by estimating the number of plants in an acre, such as 8 plants per ft2 × 43,560 ft2 in an acre.
2. Count the number of infected plants in 10 ft2 and divide by 10.76.
3. Multiply the number of infected plants per ft2 × 43,560 ft2 per acre.
4. Divide the number of infected plants per acre by the total number of plants per acre and then multiply by 100 and you have the percentage yield loss.  
5. Multiply your estimated yield (40bu/ac) by the percentage yield loss.
6. Multiply the bu/ac yield loss by the estimated price of canola.

Example:

1. 8 plants ft2 × 43,560 ft2 acre = 348,480 plants/acre
2. 5 infected plants per 10ft2 ÷ 10.76 = 0.46 plants ft2
3. 0.46 plants ft2 × 43,560 ft2 = 20,241 infected plants/acre
4. 20,241 infected plants/acre ÷ 348,480 plants/acre × 100 = 5.8% yield loss
5. 5.8% × 50 bu/ac estimated yield = 2.9 bu/ac loss
6. 2.9 bu/ac × $10/bu = $29/ac loss

Therefore, we’ve lost $29 per acre from disease, but it would have cost us $26 an acre to apply a fungicide. So, in this example we would have spent $26 to save $29 in yield, netting a return of just 10%. I encourage everyone to take a look in late August at the canola fields they didn’t spray and estimate the level of sclerotinia. Running some simple numbers now will help you to make better decisions in the future. SL

Watch pre-harvest interval for fungicides on wheat

There was a ban placed on a load of wheat grown in Kansas in 2008 because the fields had been treated with Quilt fungicide beyond the appropriate pre-harvest interval (PHI) for that product (45 days). Most products applied at heading or flowering for control of fusarium head blight all have 30-day PHIs in wheat (32 days for Proline in barley), a duration that should allow ample time for maturity before swathing or harvest. What happened in Kansas is a very strong reminder that labels are the law and must be followed.

The following pre-harvest intervals are indicated on currently registered small grain fungicides:

* Headline is the only product that doesn't specify number of days in their PHI. Feekes 10.5 is approximately 40 days before harvest, depending on air temperatures. SL

Source: http://www.ext.nodak.edu/county/goldenva/aug08news.htm

Market News

Commodity Fundamentals

Wheat Production in Million Metric Tonnes							Ending Stocks 5-Year Avg	Sep Ending Stocks vs. 5-year Avg
Crop	Production			Ending Stocks
	2008-09	Aug-10	Change	2008-09	Aug-10	Change
Rapeseed	57.9	56.7	-2%	6.7	4.8	-29%	4.6	4%
Barley	154.9	127.9	-17%	30.6	21.3	-30%	25.7	-17%
Wheat	683.2	645.0	-6%	165	174.7	6%	138.6	26%
Corn	794.7	831.5	5%	147	139.1	-5%	125.9	10%
Soybeans	211.7	253.6	20%	42.8	64.7	51%	54	20%

Technical Analysis

Canola: November futures. The short and long term trend is up.
HRS Wheat: December futures. The short and the long term trend is down.
Corn: December futures. The short and long term trends are down.
Soybeans: November futures. The short term trend is down and long term trend is up.
Canadian Dollar: August futures. The short term trend is up and the long trend is down.
US Dollar Index: August futures. The short term trend is down and the long term trend is up.