Every acre sprayed on the farm is an investment. But even the best herbicide, fungicide or insecticide can’t deliver its full value if a few overlooked details chip away at performance before the sprayer ever reaches the field.
That’s the message Fred Whitford, Purdue University pesticide safety specialist, shared during the 2026 Farm Journal Corn & Soybean College. As crop protection products continue to represent one of the largest input costs on the farm, Whitford says growers have more to gain by tightening up application basics than many realize.
“We’ve gotten very good at selecting products and spraying at the right time,” Whitford says. “Now it’s about fine-tuning the basics to get every dollar’s worth out of those products.”
From accurately measuring dry formulations to checking water quality and properly storing products between seasons, Whitford highlighted four often-overlooked practices that can improve weed, insect and disease control while protecting both input dollars and your return on investment.
1. Stop Measuring Dry Products by Volume
One of Whitford’s biggest concerns is how many custom applicators and farmers still measure dry herbicides by volume instead of weight.
It’s an easy mistake to make. Many dry products come with manufacturer-provided measuring cups or tubes, but some of those tools can be surprisingly inaccurate.
Manufacturers often acknowledge tolerance margins ranging from to as much as , meaning an intended application rate can quickly result in costly over- or under-application.
Another common trap is confusing fluid ounces (liquid) with dry ounces.
“They’re not the same,” Whitford says. “A fluid ounce measures volume. A dry ounce measures weight.”
To fix this, Whitford suggests one of the most cost-effective investments a farm can make is buying a simple digital scale to weigh dry formulation products. Such scales require less than $100 investment.
2. Don’t Skip the Adjuvant or Surfactant
When budgets get tight, adjuvants and surfactants are sometimes viewed as optional. Whitford says that’s a costly mistake.
Surfactants, crop oils and other spray additives are designed to help herbicides spread across the leaf surface, stick to the plant and move through waxy or hairy leaf tissue instead of rolling off or evaporating.
“A surfactant helps break the surface tension,” Whitford says. “Every drop has to reach the leaf and penetrate it for the herbicide to work.”
If the label requires an adjuvant, he says there’s a reason.
“If the label tells you to add something and you don’t want to spend the money, then choose another product that doesn’t require it,” he says.
Whitford also points out that manufacturers often don’t always profit from the adjuvants they recommend you use, making it even less likely those recommendations are spelled out. His point: “They put it on the label because it improves performance.”
3. Your Water Could Be Neutralizing Product Efficacy
Water quality may be one of the most overlooked factors affecting product performance on the farm.
“Can your water influence how well products work? Absolutely,” Whitford says.
For instance, hard water containing high levels of calcium and magnesium can significantly reduce the effectiveness of glyphosate.
Those minerals often bind with the herbicide in the tank before you even spray it, rendering it ineffective, at best.
“Once glyphosate binds up, it can’t penetrate the leaf,” he explains. “It’s sitting on the surface instead of doing its job.”
A Simple, Inexpensive Way To Test
Whitford encourages growers to routinely check spray water pH and hardness with inexpensive swimming pool- or spa-style test strips.
While they’re not as precise as a laboratory water analysis, they can quickly identify water quality issues that may reduce product performance.
For hard water — especially above about 450 parts per million — he recommends ammonium sulfate (AMS), with dry flowable AMS remaining his preferred option.
“All the data shows bagged ammonium sulfate is still the gold standard,” he says.
The reason for that is the “highest percentage” products are Dry Soluble Spray-Grade AMS formulations. They commonly contain 99% to 100% pure Ammonium Sulfate crystals.
Liquid AMS is less hassle to add to a tank. But to match the performance of dry AMS, you must scale up the liquid use rate to equal the amount of dry AMS used per 100 gallons of water.
Water pH matters, too. While hardness and pH are separate issues, both influence product performance and tank stability.
Water pH is a measure of its acidity or alkalinity. The scale runs from 0 to 14, with 7 being neutral.
Most pesticides perform best when spray water falls between a pH of 4.0 and 6.5. As pH rises, some active ingredients begin breaking down more rapidly.
“The higher the pH, the faster some products lose activity,” Whitford says. “In some cases, you’ve already lost a significant amount before you finish filling the sprayer.”
4. Don’t Let Chemicals Age in the Shed
Good inventory management can protect both product performance and your investment.
Whitford says pesticide manufacturers must demonstrate to EPA that products remain stable in their original containers for at least three years. Beyond that, the risk of degradation increases, particularly among inert ingredients that help the active ingredient perform properly.
“When I walk into a shed, I’m looking for products that have been sitting there for years,” he says.
His advice to farmers:
- Date every product when it arrives on the farm.
- Rotate inventory so the oldest products are used first.
- Train employees to pull older inventory forward.
- Avoid leaving opened containers sitting from season to season whenever possible.
One farm Whitford visited recently uses a whiteboard to track product arrival dates, making inventory rotation part of its standard operating procedure.
He warns that changing herbicide programs because of price, availability or resistance management often leaves partially used products forgotten on the back shelf.
“Once you put them back there, they’re never coming out,” Whitford says.
Opening a container also begins exposing the product to oxygen, which can gradually reduce quality over time. “If possible, use opened products during the same season,” he adds.
