Soybean School: Fungicide strategies for slow developing crops

Soybeans can be called the ugly duckling of the crop world. Sometimes slow to emerge, especially under less-than-ideal conditions, soybean fields can look pretty stagey and ragged in late June to early July.

However, Ken Currah of BASF says that soybeans can really surprise a grower — both in how quickly an uneven field can catch up and by how much yield can be made in August and the later part of the season.

When considering a fungicide program, establishing a low, medium, and high risk ranking of fields can pay dividends. But just because a field is uneven or a little behind doesn’t automatically zero out the risk level.

Beans tend to even up once the summer solstice has passed and each plant’s biology turns its attention to reproduction.

“If we have good fertility underneath them, we have a nice stand, they’re well managed, and we get timely rains, beans make yield the last half of the season,” Currah says. The fungicide decision, by definition is a plant protection decision remembering that that yield is made later.

Currah adds that uneven stands can catch some farmers by surprise on flowering timing. Whether employing a one- or two-pass fungicide system, early protection on those very first flowers matters. It’s a preventative approach to white mould control, he says, so it’s better to be a little early than too late. (Story continues below video)

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And what about a multi-product pass? Is it smart to add product to try and save a pass?

A tough start to the bean crop has meant that weed control is perhaps not where we want it to be, Currah says. That has some farmers asking if it’s worth adding a herbicide to the fungicide pass.

Currah says if a tank-mix is appropriate, two products is usually the max he recommends overall. There’s a few reasons for this, including the potential for antagonism, poor mixing, or, perhaps most importantly, improper timing of one of the products.

Fungicides already have a strong surfactant in them, he adds, because they are usually applied to a reasonably large crop with a thicker cuticle — and that can spell trouble if adding a third or even fourth product to the same tank.

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