Poor ground conditions and slug activity at planting over winter have left many winter crops thin and patchy across the country.

Decisions will need to be made on these crops in the coming weeks, so farmers should monitor their crops and take plant counts on these fields to assess crop viability.

Speaking at the Teagasc National Tillage Conference last week, Shay Phelan told attendees that depending on the results of these plant counts, a farmer may decide to retain a normal crop management strategy to achieve the target yield; they might resow if the crop is not capable of economic return, or the crop management plan may be altered by reducing inputs to match the lower potential yield of the crop.

Plant count thresholds

The plant count thresholds recommended for each approach with each crop are found in Table 1. These thresholds are based on relatively even plant distributions. Where fields are very patchy, it can be more difficult to decide on a course of action.

Attendees were told that replanting decisions should be based on economics, not aesthetics.

A very thin crop of winter wheat can recover and establish a decent yield.

In late 2018, Garrus winter wheat trial plots with 60 to 80 plants/m2 yielded 85% of the control plots.

It was also noted that hybrid winter barley varieties can cope with a lower plant count, as they have a greater ability to tiller and compensate for a low plant stand. Winter oilseed rape can produce a good yield with as little as 10 plants/m2.


Where thin crops are above the replanting threshold, farmers also need to be wary of front-loading nitrogen. While it may seem intuitive to try and give the crop an early kick to get it going and start tillering, farmers need to ensure there is adequate growth so that the nitrogen is used before it is lost through leaching.

Potassium and phosphorus applications can also be reduced on thin crops, as there will be a reduced crop offtake, as shown in Table 2.

Disease control is another area where savings can be made. Disease pressure should be lower on late-drilled or thin crops on which less fertiliser has been applied, so lower fungicide spends may be warranted.

Table 3 shows the cost of resowing a failed winter crop with a spring crop. The cost of sowing the failed crop, the seed used, and any herbicide applied must be carried by the spring crop. Therefore, it may not be economical to replant with a spring crop this year. Spring malting barley has the best opportunity to make a return from a resown crop.

Leaving an area fallow or planting a cover crop to repair the soil structure may be a better option in some situations.

If a herbicide has been applied to the failed crop, farmers must check the herbicide’s label to validate how soon the crop they are resowing with can be planted after the herbicide application.

Finally, farmers were reminded that winter wheat can be planted up to mid-February, but the risk of vastly reduced yields or failed crops can increase dramatically after this time.