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June 3, 2020

Cropwatch South

Our wheats have been racing through their growth stages, going from GS32 to GS39 in only 14 days. As we start on our T2s, the boots are already swelling on some crops and it won’t be long before ears begin to make their appearance.

Even with flag leaves fully out, we’re not rushing into spraying. The dry weather has held Septoria back nicely, the strobilurins we included in all our T1s have done a good job on rusts, and we are comfortably within our 21-day T1-T2 interval.

Unlike those who didn’t prioritise yellow rust early enough and are seeing it widely – and, very worryingly, on previously strong varieties like KWS Siskin – most of our crops are encouragingly clean. With so much of the disease about, we certainly won’t be taking any chances here at T2, though. As temperatures increase, protecting ourselves against the brown rust so many of today’s varieties are so susceptible to will be as much of a priority. And, knowing how rapidly early summer rain can bring it on, we shan’t be forgetting Septoria either.

This underlines the value of planning our T2s around Solatenol. It has to be the SDHI of choice against both brown and yellow rust. While it may not have the immediate Septoria activity of other SDHIs, its superior protective persistence is just what we need too. In most cases, we’ll be pairing it with our preferred epoxiconazole/metconazole co-formulation to rotate the triazoles and save prothioconazole for where we really want it at T3.

The valuable wheat responses we’ve seen from low rates of boron in recent years means we’ll be including it with most of our T2s, along with the extra magnesium important for grain set.

Our spring barleys are also full of promise, having just had their T1s. With broadleaved herbicides and trace elements as well as fungicides, some of these mixes were quite ‘challenging’ – even without the sharp frosts we had in the second week of May. So, we shied away from a PGR to follow-up our early spray to stimulate tillering.

Instead, we will be putting it on with folpet (now we’re beyond chlorothalonil use-up time) at GS37. We find this timing particularly useful for ramularia control and it will avoid the temptation to bring our bixafen-based T2s forward as well as guarding against any sudden growth spurts with almost the inevitable June rain.

Although the least soil movement at drilling, good tillering and a great canopy size means our barleys are hanging onto soil moisture fairly well, they could definitely do with another drink. If our OSR doesn’t get some moisture soon pod fill could be disappointing once again.

But we’re on the horns of a serious dilemma here. Significant rainfall will trigger the sort of orange blossom midge emergence that would seriously challenge the many quality wheats in the ground without resistance. At best, pyrethroid labels offer OWBM reduction and those that do aren’t the least harmful to beneficials either.

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