Ontario Field Crop Report

Cool weather and significant rainfall have left many fields, like this one, saturated and with little field work completed during the month of April.

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Week of April 29th, 2019

Compiled by OMAFRA crop specialists

Weather conditions: Cool and wet conditions throughout much of the province have prevented any meaningful field work from happening during the month of April (Figure 1). A string of warmer, drier weather is needed before the 2019 planting season can get moving at a steady pace. Naturally, this delay causes anxiety amongst the farming community, but experienced farmers will remind us that such delays have happened in the past and the crop always gets planted. The challenge, of course, is having the patience to wait until soil conditions are suitable for planting. Soil conditions at the time of planting take priority over calendar date.  

Winter Wheat: The most significant story with the 2019 winter wheat crop has been identifying how much of the crop is worth keeping. The potential for a significant amount of acreage to be terminated is possible, so securing seed and inputs for “plan B” should be a priority. All indications are that there will be enough soybean and corn seed available to plant into terminated acreage, however they may not always be your first choice of cultivar.

Early planted winter wheat that overwintered in good condition is now approaching Zadok’s growth stage 30 (first node). Less than 25% of winter wheat acres have received a nitrogen application. This delay is unlikely to significantly affect grain yield since weather conditions to date have been so cool and wet. There are weeds starting to show up in wheat fields (Figure 2 and 3). The good news is that winter wheat is extremely competitive and yield losses from weeds in research trials are only about 3% on average compared to a 50% reduction in corn.

Soybeans: Early planting is less critical to yield for soybeans than corn. Soybeans planted in mid-May often have the highest yield potential (Table 1). Something to consider while waiting to get in the field is seed size.  Soybean seed size tends to be large this year and this has implications for planting equipment. Ensure that your equipment is setup to deliver whole seed effectively to the ground. A split seed will not survive. 

A question that has come up this spring is if a winter wheat or even corn field has received nitrogen already, but the crop is then terminated and replanted to soybeans, does the applied nitrogen cause problems for the soybean crop?  Generally, there are no issues that arise from fertilizing soybean with nitrogen unless levels are well over 100 lb/ac of N.  The soybean crop will simply use the fertilizer N before it fixes nitrogen from the atmosphere.  In extreme cases where there is excess nitrogen the beans may get lush and be more susceptible to white mould or lodging but they still pod up normally.  Fertilizer N will delay nodulation if amounts exceed 50 lbs/ac.  It is theoretically possible for nodulation to be so delayed that yields suffer from insufficient nitrogen in late summer, however, field experience has shown this rarely happens in Ontario.

A Canada fleabane rosette on April 30, 2019

Corn: Unless you were really pushing the window on maturity in your pre-season selections, the general recommendation is to stay with an adapted hybrid until May 15-20th in shorter heat unit areas of the province (<2,800 CHU), or to the end of May in the longest heat unit areas (>3,200 CHU) (see Table 2). Two key pieces for ensuring the corn crop gets off to a good start are planting into “fit soil” and ensuring a proper and consistent planting depth into moisture. A good starting target is 1.5 – 2 inches. One inch is often too shallow. Uniform planting depth into moisture ensures uniform emergence which makes for more uniform growth staging throughout the season.  The correct depth ensures plants are well anchored and located for rapid, uniform emergence and season long standability. 

Forages: Many alfalfa stands in central and eastern Ontario are in bad shape after a winter with several thaws and plenty of standing water this spring (Figure 4). Some fields have less than one live plant per square foot. The main concern is that growers may be unaware of how severe winterkill is on their farms, because forage fields may not have been scouted. Refer to the article “Check Alfalfa Stands this Spring and Make a Plan” on www.fieldcropnews.com for more information. 2018 seedings seem to have overwintered slightly better than established stands.

Alfalfa winter kill observed in eastern Ontario during the week of April 29, 2019.

Alfalfa that is more than a year old is auto-toxic and cannot be patched with alfalfa as the seedlings will not germinate. Stands can be patched with red clover or grasses, though fields patched in 2019 will likely need to be terminated and rotated for 2020. Some producers are considering a short-season silage corn to feed out as green chop to stretch through until next corn harvest.

The effect on soybean planting date on yield (Source: OMAFRA Agronomy Guide for Field Crops, Publication 811).

Other options for annual forage include cereals or cereal/pea mixtures, Italian ryegrass, or sorghum-sudangrass. Growers in the Ottawa Valley are talking about using forage soybeans as an annual legume crop. There is an infosheet on growing soybeans as a forage crop on the OMAFRA website (www.omafra.gov.on.ca/english/crops/facts/soybean_forage.htm).

Pastures are off to a slow start. Even though there is virtually no feed in pastures yet, some livestock have already been turned out. With the wet conditions this poses a pugging risk, and the early grazing will reduce overall yield for the year. Conventional wisdom says for every day of grazing too early, a pasture loses three days’ worth of grazing in the fall.

The effect on soybean planting date on yield (Source: OMAFRA Agronomy Guide for Field Crops, Publication 811).

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