The College of Agriculture, Food and Rural Enterprises (CAFRE) has issued a crop management update, covering cereals and potatoes.
Crops specialist, Leigh McClean, said: “Frustratingly, spring weather has limited opportunities to get spray and fertiliser applied at the ideal time.
“T1 fungicides will likely have gone on later than planned for most winter crops. Keep an eye on crop growth stage and aim to apply T2 sprays at the correct time, even if the interval from T1 is shorter than usual.
“Growers should have products and plans in place to spray when the time and conditions are right, protecting what yield potential that exists.”
CAFRE
Where winter barley crops are concerned, the CAFRE advice is to target crops with T2 sprays when the flag leaf and the first few awns have emerged.
Best control of the main yield robbing barley diseases, rhynchosporium, net blotch and ramularia is achieved with a mix of active ingredients, rather than straight products alone.
Turning to winter wheat, McClean said that a well timed T2 fungicide gives a bigger yield response in these crops than any other spray timing.
AHDB fungicide trials have shown that the active ingredients mefentrifluconazole (Revysol) or fenpicoxamid (Inatreq) give best septoria control and may be worth the extra spend at T2, particularly for high yield potential crops under high disease pressure.
Where yellow rust is an issue, benzovindiflupyr and prothioconazole (Elatus Era) are particularly effective, but all good mixtures perform well.
According to the CAFRE crops specialist, in order to maximise current and future efficacy of cereal fungicides, growers must minimise the risk of resistant disease strains developing.
Practical steps include following label advice on applications per season, only using products where necessary, keeping up dose rates of actives in mixes and always using in combination with a multisite fungicide, like Folpet, to protect other active ingredients in the mix.
Spring crops
CAFRE is confirming that almost all spring sowing is late this year.
Generally, warmer temperatures and longer daylight hours from now on means that crops growing into the ground will now develop faster than those drilled earlier in the season.
According to McClean: “If the chance for pre-emergent herbicide in spring cereals has passed, then growers should apply a mix of at least two broad-spectrum herbicides, ideally when weeds are at the two-four leaf stage.
“Tank mixing a low rate fungicide will prevent disease becoming established and protect yield potential.”
Nitrogen (N) top dressings should be applied to spring cereals, once tramlines are visible, at the two-three leaf stage.
Once protein crops have emerged, they should be inspected for grass weeds and volunteers.
If necessary, a graminicide (grass weed herbicide) should be applied once most grasses are through and before the crop canopy closes over.
Experience has shown that a fungicide to control chocolate spot, normally applied in mid-June, gives a yield response. However, it can keep crops green longer, delaying harvest.
McClean continued: “For late sown beans, growers should consider forgoing fungicide, sacrificing a little yield for the chance of an earlier harvest.”
Potatoes
With the rush to get potatoes into the ground, growers are being reminded to ensure they fully implement early weed control measures.
“Where using pre-emergence herbicides, growers should check crop emergence regularly to ensure they are applied on time to avoid crop damage,” Leigh McClean commented.
Whilst blight spraying may seem some time off at this stage, control of the disease starts now. Growers should minimise sources of infection by covering out grade piles and controlling ground keepers.
As this may be more challenging this spring given the area of unharvested potatoes from last year, vigilance is advised in this context.
McClean said: “Growers do not need reminding of the difficulties associated with blight control last year.
“Disease pressure was high and whilst growers largely succeeded in getting sprays on at the right intervals, blight control may have been compromised by the choice of product going into the tank. “
He continued: “Blight consists of a population of different strains which evolve year to year. Some strains have successfully developed resistance to certain groups of active ingredients, rendering them ineffective against those strains.
“In this context, advice for blight control has also evolved. Previously, spraying blocks of a product was deemed best practice. Now, growers are advised to alternate, not just products, but modes of action at every spray.
“Applying a single mode of action at any timing is now considered too big a risk, and two active ingredients should be in the mix at each blight spray application.”
McClean said that the “increasing complexity in compiling an effective blight spray programme means growers should consult their agronomist to develop a plan for the upcoming season.
“This should adhere to all product label requirements and protect the investment made in potato crops.”
