When we think about getting the highest yields and the best quality out of our winter wheat crop we tend to think about management practices such as timely planting, variety selection, nutrient management (nitrogen, phosphorus, potassium and sulphur), as well as timely fungicide and herbicide applications. However, one management practice that can often be overlooked or forgotten about in terms of managing wheat quality is a timely harvest. As winter wheat harvest quickly approaches don’t forget to plan ahead to ensure you maintain the highest quality wheat possible by reducing your pre-harvest sprouting and fusarium risk.
Sprouting Management
Pre-harvest sprouting can result in downgraded wheat at the elevator meaning a lower return for your crop. Thus, it is important to prevent sprouting once the wheat crop reaches maturity. The most pre-harvest sprouting tolerant wheat is hard red wheat, followed by soft red wheat and white wheat which lacks sprouting tolerance. Previous research conducted in Ontario has shown that when harvest was delayed by two weeks the amount of sprouted wheat increased by almost 10% and yield was reduced by almost 4 bushels/acre (Table 1). Not only is yield being lost but the wheat is also likely to be downgraded as a result of the increase in sprouted wheat.
Table 1. The impact of delayed harvest on sprouts in winter wheat. Johnson et al. 2011.
|
Harvest Date
|
Yield (bu/ac)
|
Test Weight (lb/bu)
|
Sprouts (%)
|
|---|---|---|---|
|
July 13
|
92.4
|
62.0
|
0.0
|
|
July 18
|
91.8
|
61.3
|
0.0
|
|
July 21
|
91.7
|
60.4
|
2.3
|
|
August 1
|
88.7
|
57.8
|
8.8
|
Therefore, when planning your harvest you should combine fields with soft white wheat first to reduce sprouting risk. It is also important when planting winter wheat in the fall to ensure you are planting no more white wheat than what you are able to harvest in a few days.
Fusarium Management
In 2016, Ontario grew some of the highest quality winter wheat ever. This was a result of the very low levels of fusarium and DON in the winter wheat crop. Dry weather during the flowering period likely played a signifcant role in this. However, that is not likely to occur every year so timely fungicide applications and harvest are needed to reduce fusarium risk. If harvest is delayed and rainfall events occur before harvest is able to begin again, the quality of the wheat crop can be significantly negatively impacted. As previous research has shown, for every rainfall event that occurs after the timely harvest date, you can lose approximately 1 lb/bu of test weight (Table 2). In addition, it was found that in a field with low levels of fusarium at the timely harvest date the fusarium in the field increased significantly when rainfall events occurred.
Table 2. The impact of rainfall events on fusarium in winter wheat. Johnson et al. 2011.
|
Harvest Date
|
Yield (bu/ac)
|
Test Weight (lb/bu)
|
Fusarium (%)
|
|---|---|---|---|
|
Timely
|
73.0
|
61.1
|
0.7
|
|
1 Rain
|
72.4
|
59.6
|
1.1
|
|
2 Rains
|
73.4
|
58.9
|
1.3
|
|
4 Rains
|
72.7
|
58.0
|
1.8
|
Just as it is important to harvest white wheat first, it is also beneficial to combine fields with fusarium infections as soon as possible. This helps reduce the amount of fusarium that continues to grow particularly when moisture levels are high (>19%). The amount of fusarium damaged kerneals can also be reduced by blowing them out the back of the combine. Research conducted by Dr. Schaafsma at the University of Guelph found that when fan speeds were operated at their maximum, there was a signifcant decrease in fusarium damaged kernels (Figure 1).
Figure 1. Fusarium damaged kernels in a winter wheat sample.
Growers can be hesitant to utilize this practice because of the risk of losing good kernels. However, although this research did find that good kernels were being lost out the back of the combine, the improvement in the overall sample of the harvested grain due to reduced fusarium damaged kernels outweighed the losses of good kernels (Table 3).
Table 3. Effect of different fan-speeds on wheat yield, Publication 811: Agronomy Guide for Field Crops (Dr. Schaafsma, University of Guelph, 1996).
|
Comparison
|
Fan Speed
|
|||
|---|---|---|---|---|
|
Sieve Setting: 6mm (1/4 in)
|
Front Closed
|
|||
|
1,160 rpm
|
1,190 rpm
|
1,220 rpm
|
1,250 rpm
|
|
|
Good kernels on ground
|
16/ft2
|
11.6/ft2
|
31.6/ft2
|
24.4/ft2
|
|
Loss
|
0.8 bu/ac
|
0.6 bu/ac
|
1.6 bu/ac
|
1.2 bu/ac
|
|
Loss at 60 bu yield
|
1.38%
|
0.97%
|
2.63%
|
2.03%
|
| Comparison | Fan Speed | |||
|---|---|---|---|---|
| Sieve Setting: 6mm (1/4 in) | Front Closed | |||
| 1,280 rpm | 1,320 rpm | 1,330 rpm | 1,330 rpm | |
| Good kernels on ground |
35.2/ft2
|
41.4/ft2
|
43.6/ft2
|
42.8/ft2
|
| Loss |
1.8 bu/ac
|
2.1 bu/ac
|
2.2 bu/ac
|
2.1 bu/ac
|
| Loss at 60 bu yield |
2.93%
|
3.45%
|
3.63%
|
3.56%
|