Few signs of disease but ground conditions are already messy

RAIN in mid May was very welcome for our late spring sown crops but enough is enough. While last week provided very few spraying opportunities, ground conditions, particularly in potato fields were very messy.

So far there are very few of our wet weather diseases evident in crops but while there is very little rhyncosporium there are some worrying levels of net blotch. Keep an eye on Planet, Mickle and Propino which are all rated at 5 on the Department’s recommended list.

Mildew is widespread across all unsprayed spring barleys. In general, there is very little BYDV evident in unsprayed crops in the Midlands — both early and late sown.

Crops sown after ley or very grassy stubbles are the worst affected but even those are showing less than 5pc affected. Spring barley crops with high plant stands and high tiller counts may benefit from the use of a growth regulator — watch growth stage restrictions carefully — gs 32 for CCC, Moddus, Optimus; gs 39 for Terpal, Cerone and Medax Max.

The best result will be got by applying them early rather than waiting for the latest possible timing.

Late timing and application to thinner crops tends to give an increase in green tillers at harvest and to ears remaining erect.

T2 fungicide applications to spring barley have just commenced. Crops have a long way to go to harvest so maintain robust rates or delay a little longer if your T1 cover and disease levels permit. The ideal timing is during awns emergence.

All final sprays should include either Chlorothalonil or Foilpet to provide protection against ramularia and perhaps more importantly to help protect your main fungicide(s) from resistance by diseases.

Combination products such as Bontima, Ceriax, Deuce and Diamant, Elatus Era, Siltra/ Mandarin, Fandango/Mettle and Treoris may be selected based on price, their fungicidal activity and crop disease levels and crop yield potential. Winter wheat is looking good at present with most crops having four/ five green leaves — much of the credit for that must go to dry weather conditions up to mid May.

While it is dangerous to get complacent it is unlikely that septoria will cause the level of devastation that was feared earlier in the year. Mildew is present in may crops on stem bases and the lower leaves and there is a high risk that it will move rapidly to the head – Prothioconazole or Corbel, Tern Winger. Rust is widespread in susceptible varieties including JB Diego. Splashy rain at flowering – and we are seeing plenty of that – brings a real risk of Fusarium. Products to be considered include Prosaro, Magnello and Folicur. In all cases include Chlorothanonil. Add Dimethoate if aphids are present.

Spring wheat

Spring wheat crops are generally clean. Where possible wait for full flag leaf to apply your main fungicide which might be Treoris plus a triazole, Adexar, Librax. Elatus Era, Ascra,

Monitor spring oilseed rape crops carefully from the green bud stage to the onset of flowering for pollen beetle. The risk is particularly high in areas where spring crops are adjacent to winter rape.

The suggested threshold for insecticide application is one beetle per plant.

Insecticides should not be applied to oilseed rape without first notifying local beekeepers — www.irishbeekeeping.ie will give you contact details for the local beekeeping associations.

The advance of sterile brome in continuous winter barley land is an ever increasing problem. Now is the time to map areas that are infested and to put a plan in place for future control.

Much of the original infestation is due to contamination from field margins.

The biggest culprit at this stage is the combine with seed heads been picked up and transported from contaminated areas of fields to clean areas and from contaminated fields to clean fields.

Mapping contaminated areas now and cutting only clean areas first may appear unrealistic but is a far better option than finding in a few years time that you have to reseed fields and to stop growing winter barley.

INSECTICIDES SHOULD NOT BE APPLIED TO OILSEED RAPE WITHOUT FIRST NOTIFYING YOUR LOCAL BEEKEEPERS

PJ Phelan is a tillage advisor based in Tipperary and is a member of the ACA and ITCA