Winter wheat crops quickly advance, alfalfa weevil seen active

Ontario’s crop season continues to be advanced of normal, which is especially evident in perennial and over-winter crop development. Crop heat units (CHU) and growing degree days (GDD) are significantly above the 10-year average, especially in southern Ontario. Progress for field work, particularly on heavier-textured soils has been limited due to frequent patchy rain, cool nights and overcast conditions. Manure application, fertilizer application, burn-down herbicide applications and tillage ahead of planting has occurred on well-drained fields as conditions allow.

Cereals

Winter wheat crops continue to progress ahead of normal which has caught some growers off-guard when scheduling field applications for nutrients and pesticides.  Early planted fields and fields in the south are about 2 weeks ahead of normal and are at or near heading. Many will have T3 fungicide applied within the next week for protection against Fusarium.  Fields further north and east and later planted fields are about 1 week ahead of normal.

Barley yellow dwarf virus (BYDV) has appeared in early planted wheat, as well as in winter barley.  Spread by cereal aphids, the primary symptoms are stunting and discolouration of leaf tips (yellow, red/purple). Early planted wheat last fall, as well as fields surrounded by cereal cover crops, is at higher risk of infection. Insecticide seed treatment may need to be utilized if planting very early in the fall.

Physiological fleck is also appearing in fields and is often mis-diagnosed as a disease.  Some varieties are more susceptible and generally symptoms are more uniform across the field than diseases and do not move upwards in the plant like diseases such as septoria. 

Powdery mildew is appearing in winter wheat fields with thick canopies due to the wet weather.  Some infection is appearing on the penultimate leaf and has growers wondering about the need for control. In most cases, if the variety has some level of resistance to powdery mildew and is nearing heading, a fungicide application can wait until T3. There were differences reported in powdery mildew control between fungicides.  It is important to read fungicide labels to ensure the fungicide is labelled and has efficacy for the disease to be controlled.  An updated Ontario Crop Protection Hub is a great resource for comparing pest control options.  It is important to ensure the correct pest is selected when comparing products.

Stripe rust has been found in winter wheat in Essex (Maidstone), Chatham-Kent (Tilbury) and Elgin (St. Thomas) counties. The best defense against stripe rust is a combination of variety selection, scouting and timely fungicide applications. In Ontario winter wheat varieties, there are large differences in variety susceptibility to the disease. Growers should check with their seed supplier and the Ontario Cereal Crops Committee performance trials for specific variety ratings. If a variety has a rating of 6 or higher, the variety is susceptible to stripe rust and will benefit from a fungicide application if stripe rust is present. If a variety is rated 3 to 5 then it is considered moderately resistant and should be scouted for stripe rust regularly during the growing season. If stripe rust is present and appears to be challenging the upper leaves of the canopy in these moderately resistant varieties you may want to consider a fungicide application, particularly if the wheat is just at flag leaf. If stripe rust incidence and severity is low on tolerant varieties and growers are less than a week away from fusarium fungicide timing, then you can wait until T3 fungicide timing. If a variety in your area has a rating less than 2, this indicates that the variety is resistant against stripe rust and will likely not benefit from an early fungicide application.

Forages

Grasses and forage cereals are progressing quickly. Many fields of winter cereals intended for forage are beyond the flag leaf to boot stage where protein and digestible fibre quality is highest. Once the crop heads out, forage quality declines quickly. A second opportunity for cereal forage harvest occurs for whole-crop cereal silage at soft dough stage, much like corn silage.  The cereal can be chopped and ensiled in a tower, bunker, or bag. Soft dough stage is too late for bale age, since stems will poke holes in the bale wrap. Although highest quality comes with forage harvested at boot stage, the maximum energy harvested per acre occurs at soft dough stage.

Growers harvesting dairy alfalfa forage by the calendar will begin harvest within the next week.  Wet fields and busy planting schedules often give priority to timely corn planting, however timely forage harvest will give bigger economic benefit from a livestock nutrition perspective with higher digestible fibre versus higher lignin with later harvest.  It is easier and less expensive to replace the energy lost from late planted, lower-yielding corn than it is to replace lost digestible fibre from a late forage harvest.

Alfalfa weevil have been active in some fields in the south.  Regular scouting, looking for tip feeding with 2 to 3 active weevil per stem will determine what type of action is required.   Harvesting the field is the best option, however, watch for feeding on regrowth if larvae are small.  If the forage crop is not ready for harvest, then insecticide control for alfalfa weevil may be required.  

Manure application after forage harvest is a good opportunity to supplement nutrients removed by the crop, especially in forages that include grasses.  Application as soon after harvest, before regrowth, will provide best results, since yield will be reduced where delayed wheel traffic sets back new growth.  After application, alfalfa regrowth occurs at the apical buds on the stems and from the crown, but alfalfa regrowth damaged by wheel traffic will need to re-start from the crown. Taking a manure sample is recommended, since most manure applications to alfalfa forage crops will not replace the potassium that is removed by the crop.

Corn

Planting progress as of May 16th ranges between 25 to 40% completed, however this varies from regions where no planting has occurred to light soils where planting is close to completed.  Seed bed preparation has varied with spring rainfall where pounding early spring rains have left seedbeds lumpier than areas with fewer and gentler spring rain events.   Late April planted corn has emerged.  Producers looking at the calendar are asking about switching varieties. Switching to shorter season hybrids is not recommended until after May 25 if conditions continue to prevent planting opportunities.

Weed control

Even when conditions will delay planting for several weeks, it is important to apply burndown treatments when weeds are small and actively growing. 

With delayed spring operations, there will be an overlap in spraying schedules across various crops.  Tank cleanout and communication with the spray applicator on what herbicide tolerant crop traits have been planted will avoid costly errors.

Agricorp wants to remind growers to report their acres as soon as they finish planting to avoid last minute rush.  Reporting can be done online or by calling in to the Guelph office.

– To read the original report on the Field Crop News website, click here.