Ontario Field Crop Report – July 27, 2022

Weather Conditions

The percentage of average precipitation during the current growing season is quite variable across the province. Crop conditions generally mirror precipitation levels with below average precipitation received in mid-western and southern Ontario causing significant crop stress, especially on lighter textured soils. Conversely, parts of eastern Ontario are above average with generally good crop conditions.

Wheat Harvest

Significant progress has been made on winter wheat harvest. Yields between 90-110 bu/acre have been common, but have ranged from the low 70’s on sandy soil to the low 140’s. In general, the 2022 winter wheat crop has been of good quality and yield.

Nutrient removal from baling straw

There is always a debate over whether straw should be sold, based on its value for soil organic matter. Long term rotation research at the Elora Research Station has clearly demonstrated that the value of cereals in the rotation, even with straw removed, far outweighs any negative impact of straw removal. Even with straw removed and no cover crop (red clover), yields of subsequent corn and soybean crops increased dramatically (corn 12%, soybeans 14%), and soil health parameters, such as organic matter and water stable aggregates, are improved considerably. If selling the straw improves the profitability of cereal production to the point that producers keep cereals in the rotation more frequently, then the producer should sell the straw.

Table 1 provides an overview of phosphorus and potassium levels removed from 1 ton of straw and the corresponding estimates of fertilizer costs to replace those nutrients.

Nutrient	Avg. to Max. Removal (lbs actual/ton)	Fertilizer	Fertilizer Replacement (lbs/ac)	Fertilizer Cost ($/lbs)	Value ($/ac)
Phosphorus	3.2 – 6.0	MAP (11-52-0)	6.5 – 11.5	0.60	$3.90 – 6.90
Potassium	16.8 – 42.5	Potash (0-0-60)	28 – 70.8	0.50	$14.00 – 35.40
				Total value ($/acre):	$17.90 – 42.30
				Total value (¢/lb of straw):	¢ 0.8 – 1.92

Table 1. The average to maximum amount of phosphorus and potassium removed from harvesting 2200 lbs (1 ton) of winter wheat straw per acre, along with estimated fertilizer replacement costs* presented on a per acre and per pound of straw basis.

Post wheat harvest weed management strategies

The established of cover crops after cereal harvest has been shown to reduce weed seed production and dispersal to the soil. This would be of particular benefit when trying to manage glyphosate resistant weed species like Canada fleabane and waterhemp. Some highlights from recent studies include:

• Fall planted cereal rye on sandy soils reduced glyphosate resistant Canada fleabane biomass by as much as 96% in one University of Guelph study.
• A second University of Guelph study that evaluated cover crops planted in the fall on heavier soil textures revealed that glyphosate resistant Canada fleabane biomass the following season was reduced by 36% with oilseed radish, 41% with oats, 52% with crimson clover and 57% with cereal rye.
• A University of Missouri study demonstrated that fall planted cereal rye reduced early season summer annual weed emergence (including waterhemp) by 41% the following season.
• A University of Arkansas study observed up to a 69% reduction in Palmer amaranth seed production where a cereal rye cover crop had been planted.

If you’ve never planted a cover crop after winter wheat harvest, oats is a good one to start with. Its relatively inexpensive, easy to establish, does not over winter and could be used for extra forage feed if the opportunity exists.

Managing weeds in red clover following cereal harvest

If red clover was under-seeded into the wheat crop there are a couple of ways that you can knock back annual weed growth so that you can let the red clover grow as much as possible and maximize its nitrogen credit. The tried-and-true method, but most labour intensive, is to “clip” or trim the top of the red clover which will ‘chop off’ the weed seed heads at the same time. OMAFRA and the University of Guelph have experimented with applications of MCPA to manage broadleaf weeds in a red clover cover crop. There are three key learnings from this work:

1. The ester formulation of MCPA causes significantly less plant damage then the amine formulation.
2. Red clover biomass is initially stunted during the first week after application but does recover within 2-3 weeks.
3. Targeting broadleaf weeds when they are smaller will result in better control, if annual grassy weeds are predominant then the application of MCPA Ester will be insufficient and clipping is a better option to minimize weed seed dispersal.

Weather Data – July 18 – 24, 2022

Location	Year	Highest Temp (°C)	Lowest Temp (°C)	Rain (mm)	Rain (mm) April 1st	GDD 0C April 1st	GDD 5C April 1st	CHU May 1st
Harrow	2022	30.7	19.6	19.5	300	1772	1249	1872
	2021	29.5	10.7	48.7	373	1861	1305	1895
	10 YR Avg. (2011-20)	29.2	16.5	11.6	351	1850	1278	1976
Ridgetown	2022	32.2	18.1	5.0	209	1659	1145	1714
	2021	28.6	9.4	5.4	353	1754	1206	1785
	10 YR Avg. (2011-20)	29.0	14.5	16.8	300	1739	1171	1841
London	2022	33.5	17.9	19.2	222	1615	1104	1660
	2021	28.7	11.1	19.8	282	1746	1202	1757
	10 YR Avg. (2011-20)	29.2	15.3	17.7	324	1715	1152	1819
Brantford	2022	33.6	17.6	27.4	228	1612	1096	1616
	2021	29.0	10.1	14.0	264	1723	1178	1732
Welland	2022	30.2	17.5	43.1	248	1657	1132	1711
	2021	27.1	12.2	7.8	274	1718	1169	1738
	10 YR Avg. (2011-20)	28.7	15.8	16.3	308	1722	1157	1828
Elora	2022	31.8	14.7	4.8	184	1473	970	1479
	2021	27.7	10.1	49.2	241	1586	1050	1594
	10 YR Avg. (2011-20)	27.8	13.2	9.9	317	1541	990	1621
Mount Forest	2022	30.6	17.5	23.4	230	1475	978	1508
	2021	26.8	9.3	33.7	285	1587	1054	1595
	10 YR Avg. (2011-20)	27.1	13.2	22.5	322	1521	978	1616
Peterborough	2022	31.1	15.1	27.0	255	1481	963	1509
	2021	29.2	9.4	30.3	271	1583	1037	1582
	10 YR Avg. (2011-20)	28.6	12.7	9.8	279	1562	1011	1625
Kemptville	2022	30.7	18.4	24.1	372	1591	1053	1635
	2021	29.0	12.5	16.7	229	1711	1159	1685
	10 YR Avg. (2011-20)	29.0	13.3	17.9	314	1638	1088	1728
Earlton	2022	31.7	14.7	24.3	233	1328	859	1407
	2021	28.2	8.2	46.4	392	1474	947	1440
	10 YR Avg. (2011-20)	26.7	10.3	19.1	270	1296	829	1415
Sudbury	2022	29.4	15.7	31.0	242	1330	853	1410
	2021	30.5	10.7	38.3	291	1491	966	1483
	10 YR Avg. (2011-20)	27.3	12.6	17.7	298	1393	903	1516
Thunder Bay	2022	32.4	12.9	11.4	375	1113	672	1135
	2021	32.6	5.0	3.7	210	1358	845	1354
	10 YR Avg. (2011-20)	26.3	11.0	13.7	295	1213	734	1279
Fort Frances	2022	28.5	14.1	12.0	487	1196	757	1287
	2021	32.4	12.2	12.0	167	1451	932	1480
	10 YR Avg. (2011-20)	27.3	11.1	12.6	287	1340	843	1439