South: Time may not be right for new SDHI fungicides

I started my Crop Watch column last month by saying rain was desperately needed. Since then, we have had no significant rainfall and the situation is getting critical, especially on light soil types.

Oilseed rape seems the worst affected on light soils and some crops are refusing to flower and are sitting at the yellow bud stage with flowers aborting before they open. Pollen beetle are not the cause as the aborting flowers are clearly undamaged by the pest.

Crops on thin, brashy soils have been hit hardest, but damage is variable. Some crops grown on brash look really well, while others look awful – a dirty yellow colour with few if any open flowers. DK Cabernet seems one of the worst affected varieties and most hybrids generally look much better.

Wheat crops have just had a T1 fungicide application. Broad-leaved weed levels are low and in most cases growth regulation is happening naturally, so at least I could avoid complex mixes on these stressed crops. If it stays dry and hot, the flag leaf will be emerging by the end of the first week in May and fungicide choice at this stage could be interesting. If it does not rain, I cannot see many cases for using a new SDHI fungicide. In fact, the proven physiological benefits of a strobe and the cheaper cost will probably be a more sensible bet for all but the most moisture retentive land.

Spring crops planted into moisture are romping away at the moment, but trace element deficiencies are showing up in many places. Anywhere moisture was lost dry seed is sitting in the ground with little chance of chitting.

Forage maize drilling is causing headaches and my advice so far on winter ploughed land has been to avoid moisture loss as far as possible in seed-bed preparation. If sufficient moisture exists at three inches depth, plant into this and roll. But if the soil is dry at this depth, wait and see if it rains. It’s easy for me to say, but for those with low carry over stocks and the prospect of restricted grass growth this year, it is causing a lot of anxiety.


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