With March UK rainfall only 77% of the monthlyhistorical average and dry conditions continuing into April is the feareddisease season about to turn into drought?
Certainly soils at Stanswood Farm, Hampshire aredrier than liked but it is only the potatoes that are suffering at the moment.Farm agronomist Richard Cromie of Crop Management Partners says the situationisnt critical yet but could head that way. Theres still sufficient soilmoisture below the surface but we do need some rain soon. It would certainlyhelp with pre-emergence spring herbicides!
Disease levels have been checked to a degreeand the key decision now is SDHI product and rate. Here at Stanswood Farm wedo have active Septoria incrops, but it is at fairly low levels. Earlier it looked like we could have arepeat of 2014 Septoriaepidemic but the weather and well-timed T0 sprays have put us in a betterposition. Its where we go from here wet weather could see Septoria return, if it stays dry wecould be looking at drought tolerance properties of certain SDHIs to try andpreserve crop potential, he notes.
Although various physiological benefit claims aremade only Bayers Aviator235Xpro (prothioconazole +bixafen) has label claim for yield increases above disease control alone. Partof that label claim is increased chlorophyll content, something BayerCropScience commercial technical manager Tim Nicholson says could be usefulthis season. Increased chlorophyll aids photosynthesis and GLA retention.Under drought conditions light-capturing pigment chlorophyll degrades andleaves roll and dessicate.
Anything that helps reverse this has to bebeneficial. Trials with Aviator235Xpro at T2 underdrought induced conditions have also shown an average extra 13% flag leaf areaand 9% second leaf area from GS49 to GS 61.
The other impact of drought stress is restrictednutrient flow to leaves, and again there was a benefit here too. UsingInfrared thermography we found that Aviator235Xprotreated plants buffered themselves against drought stress and remained coolerindicating more normal rates of transpiration, he concludes.