Arable
Early PGRs help beat wheat disease and build yield
• Thicker crops oſten at greater risk • Tailored approach to PGRs vital • Use chlormequat alone or in a mix
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arlier application of plant growth regulators could have benefits for disease control and rooting in wheat crops this spring, according to agrono- my provider Farmacy. With crops at a range of growth stages coming out of win- ter and last season’s high lodg- ing incidence in many areas still fresh in the mind, there may be clear advantages for both forward and more backward crops, says the firm’s David Howard. Lush, thick crops are often at
greater disease risk, especially from Septoria, which is spread by rain splash within the cano- py. However, any period of rapid growth can result in soft plant tis- sue that is more vulnerable to in- fection, he says.
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An early PGR can have a big impact on root stimulation
Steady growth Growers should try to maintain steady growth throughout the season and avoid sudden surges as many experienced last spring when rain after a prolonged dry spell resulted in a flush of rapid growth, weak stems and lodging in some crops. “Because it was so dry and crops were stressed, a lot of grow- ers quite rightly, either reduced the dose or did not apply later growth regulators. By the time rains came, growth response was extremely rapid and it was too late to do much about it with PGRs.” To avoid a repeat, Mr How-
ard favours a “little and often” approach to PGRs from T0 on- wards to keep growth under con- trol, and promote other benefits, such as improved rooting.
10 ANGLIA FARMER • MARCH 2018
“An early PGR can have a big impact on root stimulation during the foundation phase up to GS30. “It’s not just about canopy con-
trol. Improving rooting should en- able all crops to access more wa- ter and nutrients, which means they are healthier, suffer less stress and are not as susceptible to disease.”
Favoured appoach It’s an approach favoured by Lin- colnshire-based Farmacy agron- omist Charles Wright, who says PGRs are generally best applied early at T0 and T1 to build root mass and manipulate canopies, rather than delaying applications and trying to rectify problems lat- er in the season.
Although early-drilled wheat is generally well developed, a lot of later-sown crops are less ad- vanced and some fields show big in-field variations in growth stag- es, so a tailored approach to PGRs will be essential. “Variety, soil type, nutrient re- gime (artificial and organic fertil- isers) and weather all influence the exact approach you take, but in general I prefer to go early and use a mixture of different PGR actives rather than relying on a single mode of action.”
Plant growth regulators work by targeting different parts of the plant growth hormone cy- cle, so using products based on a range of active ingredients will affect different parts of the growth chain and provide more effective growth manipulation than a single active, explains Mr Howard. Few PGRs are approved for use prior to GS30, but some based on trinexapac-ethyl can be applied. He suggests includ- ing these with the first T0 fungi- cide to manipulate rooting and tillering and follow with a full PGR programme at T1 and T2.
Canopy manipulation
• Thick, lush canopies at greater disease and lodging risk • Use PGRs to maintain steady growth • Early PGR use can stimulate rooting – aids water and nutrient capture
• T0 spray is key time to promote rooting and control canopy • Utilise a range of chemistry for more effective growth manipulation.
(Source: Farmacy) Other options
Chlormequat is another option that can be used alone, or in- cluded with trinexapac-ethyl if growth is very advanced. For ear- ly PGR applications when condi- tions are cooler, products contain- ing prohexadione may be another option to consider. A chlormequat plus trinexa- pac-ethyl mix is Mr Wright’s pre- ferred approach for the majority of winter wheat but he points out that warmer conditions and ac-
tive growth are needed to achieve the best results.
Dose should be tailored to spe- cific field conditions and variety. “It’s important to have a plan for what you’re trying to achieve with PGRs, but don’t be too prescrip- tive. Every field must be managed individually,” says Mr Howard. He also reminds growers of the intrinsic link between can- opy structure and nutrition, so PGR and fertiliser programmes must be managed in tandem.
Tackling Septoria risk sooner can prevent bigger problems
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