Monday, May 16, 2016

Some Risk for Wheat Crop Injury From Saturday's Cold Temps


Saturday mornings cold temperature may lead to crop injury in low lying areas across Southern WI. Based on the development in our wheat plots the highest risk for yield loss would likely come in the southern tier of WI counties. The wheat at our southern locations are either at the Feekes 8 (flag leaf visible) or 9 (flag leaf ligule and collar visible) crop growth stage dependent upon variety. 
 
Image 1. Feekes 9 crop growth stage at Arlington WI on 5/16/16.
Crop injury at these growth stages would occur in the 24 to 28 (duration of up to two hours) degree F temperature range. We did not see this temperature extreme at our Arlington location (Image 2; low temp of 30.5) however I have heard reports of extended cold temperatures in the sub 28 degree F range.   
Image 2. Arlington WI weather data for the last week.

The two types of crop injury I would be concerned about include stem damage and spikelet (head) injury. In Image 3 below you can see the brown discoloration and water soaking to wheat stems caused by freeze injury. This  injury eventually lead to severe lodging among select varieties (Image 4). If you see this type of injury it would be best to take this field as a forage crop ASAP. 

Image 3. Freeze damage to wheat stem.

Image 4. Subtle difference is crop growth stage led to severe lodging due to freeze injury.
The other type of injury would be direct damage to the wheat head. Peel back the boot and expose the wheat head. If healthy individual florets on the spikelet will appear pale green (Image 5). If they begin to appear water-soaked or off colored (brown) then crop injury occurred).  

Image 5. Healthy spikelet and florets.
For more detailed information I have attached a link to a publication entitled Spring Freeze Injury to Kansas Wheat.  For ease I have also removed a table from that publication to stress the importance of growth stage on damage potential  (Table 1).

Table 1.  Wheat Resistance to Freeze Injury (From: Spring Freeze Injury to Kansas Wheat)




Thursday, April 7, 2016

Soybean Management Strategies to Facilitate Timely Winter Wheat Establishment in 2016

Winter wheat acres across WI have declined over the past few years due to high corn and soybean prices and late grain harvests, however current economic realities suggest an opportunity for increased wheat acres moving forward. As farmers get ready to kick off the 2016 growing season here are a few suggestions to help get your 2016/17 winter wheat crop established on time.
  • Plant early. If weather and soil conditions allow for it plant the acreage you intend to go to winter wheat first. This is regardless of which crop you plan to follow (soybean, corn silage or field corn). Remember the optimal planting date window for most of our WI winter wheat acres is the last week of September through the first week in October. In Figure 1 below you will notice that for every 3 days planting is delayed we see 1 day delay in harvest, so delaying planting by one week equates to about 2 days later maturing. However when planting is delaying past June 1st it turns in to more of a 1: 1 relationship. Also remember in WI it normally takes another 5-8 days for the soybean crop to move from R7 to R8 (full maturity).
Table 1. Calendar date for reaching R5 (beginning seed fill) and R7 (beginning maturity) growth stage by planting date and maturity group for the 2014 & 2015 growing season at Arlington and Hancock, WI.


Date of Growth Stage Initiation


R5
R7
Planting Date
Maturity Group
Arlington
Hancock
Arlington
Hancock
May 1st
2.5
5-Aug.
3-Aug.
14-Sept.
15-Sept.

2.0
1-Aug.
1-Aug.
8-Sept.
13-Sept.

1.5
29-July
29-July
2-Sept.
9-Sept.
May 20th
2.5
9-Aug.
10-Aug.
20-Sept.
22-Sept.

2.0
6-Aug.
7-Aug.
14-Sept.
18-Sept.

1.5
3-Aug.
5-Aug.
8-Sept.
16-Sept.
June 1st
2.0
12-Aug.
12-Aug.
21-Sept.
24-Sept.

1.5
10-Aug.
11-Aug.
16-Sept.
19-Sept.

1.0
8-Aug.
8-Aug.
12-Sept.
13-Sept.
June 10th
2.0
16-Aug.
18-Aug.
27-Sept.
30-Sept.

1.5
15-Aug.
17-Aug.
24-Sept.
26-Sept.

1.0
13-Aug.
15-Aug.
21-Sept.
22-Sept.
June 20th
1.5
23-Aug.
21-Aug.
2-Oct.
4-Oct.

1.0
21-Aug.
18-Aug.
28-Sept.
28-Sept.

0.5
19-Aug.
18-Aug.
24-Sept.
24-Sept.
  • Crop rotation matters. Our long-term rotation data suggests winter wheat yields are greatest following soybean, followed by corn silage and lastly corn for grain.  Therefore plan your rotation accordingly to maximize yield and system efficiency.
  • Consider an earlier maturity group soybean. Plant a high yielding, earlier maturity group soybean to help get that soybean crop harvested on time. Though later maturing varieties "on-average" produce the greatest yields, data from our 2015 WI Soybean Variety Test Results show the maturity group range that included a starred variety (starred varieties do not differ from the highest yield variety in that test) was 1.9-2.8, 1.1-2.4, and 1.1-2.0 in our southern, central and north central regions respectively. This suggests that the "relative" maturity group rating is trumped by individual cultivar genetic yield potential. Therefore growers have options to plant an early maturity group soybean that will be harvested on time and not sacrifice yield.
  • Manage for the system not necessarily the crop. If you are serious about maximizing wheat grain and straw yield on your farm one of the biggest contributing factors for both of these in WI is timely wheat planting. Make management decisions to facilitate that. *We all know what inputs can extend maturity that don't necessarily guarantee greater yields. So instead of listing them and fielding angry emails I am being strategically vague here*  As a producer is it better to sacrifice 0-2 bushels of soybean yield or 10-20 bushels of wheat grain yield and 0.5 tons of straw?  
As we all know mother nature holds the ultimate trump card on whether we will get our winter wheat crop established in that optimal window. These aforementioned strategies are relatively low risk to the farmer and regardless of what weather patterns we run into are agronomically sound.