08 May 2025
Treat trace element deficiencies as soon as possible
Trace element deficiencies are becoming evident in some spring crops, Teagasc Tillage Specialist, Shay Phelan reminds us that crops need careful treatment to avoid setting them back even further.
Trace element deficiencies are becoming evident in some spring crops, Teagasc Tillage Specialist, Shay Phelan reminds us that crops need careful treatment to avoid setting them back even further.
Spring crops
The dry season is starting to take its toll on crops sown in lighter soils; magnesium and manganese deficiencies are common in cereal and break crops. This is particularly evident in later-sown crops and even in some of the early drilled crops. In spring barley, these will most likely be cured by rain but the forecast over the next week shows little sign.
Therefore, where trace element deficiencies occur get them correctly identified and treat them as soon as possible, these will result in tiller loss in barley which will affect yield.
Manganese deficiency generally displays yellowing of the leaves with brown dots along the leaf veins and is usually worse between the wheel tracks and is better under the wheel marks (see figure 1 below).
Magnesium deficiency occurs in random patches in the field and can be diagnosed by yellowing of the leaf margins and/or along the leaf veins (figure 2 below).
Figure 1: Manganese deficiency
Figure 2: Magnesium deficiency
If crops are displaying signs of either of these deficiencies – or any other stress, e.g. compaction – then these crops need careful treatment to avoid setting them back even further. Applications of herbicides or plant growth regulators should be avoided until the symptoms disappear, as these will stress the crop even more and potentially lose yield.
Winter barley
Practically all crops are at awns peeping stage at the moment, with earlier-maturing varieties like Joyau starting to flower. Therefore, most crops should receive their final fungicide in the coming days, most Joyau was treated at least 10 days ago.
There is still some debate among growers and agronomists about this timing, with some preferring to wait until flowering to keep the crop green for as long as possible. In fact, the earlier will keep the crop green for longer as ramularia is the threat at this stage.
The fungicides we currently have are only preventative in controlling ramularia and will not cure it, therefore it is essential to protect the leaves form infection. Many of the lower leaves already have ramularia on them. This will spread upwards through the crop, so by delaying the fungicide, you are allowing the disease to spread over the next few weeks and will take out leaves and the crop will then die back earlier. Options include Folpet at 100% rate + MacFare expo/ Navura/ Balaya + Imperis/ Elatus Era etc. 50-80% rate
Winter wheat
Leaf 3 applications are almost complete at this stage and some of the earlier crops will be at flag leaf stage in little over a week. Some varieties e.g. Champion, Dawsum, Fitzroy, Torp are showing signs of yellow rust infection, and this should be monitored over the coming week; if there are live pustules on the leaves, then consider applying tebuconazole +/- Comet to give 7-10 days control until the flag leaf application is due.
Not every field or variety is affected, but the varieties listed above would be a priority and should be inspected over the coming days to assess the need for a fungicide application.
Figure 3: Yellow rust is evident in some wheat crops
