Crop dusters and spray drones are taking flight, but is what’s in the tank enough to take on this year’s disease pressure? Every disease problem requires three factors for infection to occur: 1. a suitable host, 2. the pathogen, and 3. an environment conducive to growth and infection by that pathogen. A strong fungicide or insecticide application can make or break a successful cropping season, but the optimum tank mix is incomplete without the right adjuvants.
The mild winter increased the risk of insect and disease pressure by allowing more disease-causing insects and fungi to survive into spring. Some bacterial diseases that are caused by insects, like Stewart’s wilt, are ones to consider targeting since more insects survived the warm winter.¹
Other pathogens, like fungal inocula are in soil just waiting for the conditions to be right to cause tar spot, white mold, and other diseases.²
Since some hybrids are more susceptible to certain diseases, identifying which disease your hybrid has a higher risk for can help determine what actives and adjuvants will best protect your crop.
While fungicides often have activity against multiple diseases, choosing the right active ingredients is still very important to effectively manage diseases. There are several fungicides available that contain triazoles, strobilurins, or combinations of other multiple active ingredient families. These actives are effective against a broad range of fungal diseases in various crops. Veltyma®, Headline®, and Quadris® are some brand names for these broad-spectrum fungicides. Check with your local crop advisor or university extension to learn which active ingredient combinations are the most effective for pests in your region.
It’s important to note that the effectiveness of fungicides can vary depending on several factors, including the specific fungicide used, the stage of the disease, environmental conditions, the severity of the infection, and how well it reaches the target. It is always recommended to consult with local university extension services or crop advisors to determine the most appropriate fungicide and application timing for your specific location and situation. Always follow the label instructions and guidelines when using fungicides.
Ensuring maximum application effectiveness is crucial when using fungicides to control fungal pathogens. Adding adjuvants increases the likelihood that the fungicide achieves its goal by helping the actives achieve full efficacy potential. Fungicide labels are sometimes ambiguous about any specific adjuvant recommendations, but they do generally warn against drift and give recommendations for drift mitigation. Adjuvants help to deliver the application to the target (i.e., reduced drift) and help it spread and be effective on the target (i.e., improved deposition). Adjuvants allow tank mixes to be tailored to local conditions, and the behavior of the targeted diseases should be considered to best alleviate disease pressure.
The three major categories of fungicides are contact, translaminar, and systemic. Exacto adjuvants can be used to enhance each of these categories. Exacto adjuvants for fungicide applications offer properties like spreading and wetting, drift reduction, deposition, UV protection, and rain fastness. While some products like deposition aids, drift reduction agents, or surfactants perform a single benefit, others are multifunctional delivering multiple functionalities in one easy and effective formulation.
Fungal diseases can be present deeper in the canopy, so it is vital that a fungicide application will be able to be deposited on all leaves, including those lower in the canopy. A deposition aid improves canopy penetration and gets the fungicide down onto the plant’s lower leaves.
Diseases like corn tar spot infect plants from the lower leaves upward, so initial fungicide applications benefit in particular from deposition aids helping the lower corn canopy receive active ingredients. This protects corn plants before the upper leaves, which capture the most sunlight, are affected.
Drift reduction agents keep spray applications on target by fostering a more uniform and consistent spray pattern with less influence from environmental factors. Drift reduction agents “Right-Size” the spray droplets. Right-sizing means that these formulations significantly reduce the amount of driftable fine droplets, while preventing droplets from becoming too large and bouncing off of a leaf surface. This keeps the fungicide in the sprayed field and on the leaf for optimal protection.
A good surfactant will help spread the active ingredient ensuring more contact with the target. This makes it possible for the active to do its work no matter what type of functional category the fungicide falls into. If the spray application does not cover the leaf, the results of a fungicide treatment may not be as effective.
Multifunctional adjuvants offer convenience and ease of use by combining multiple functionalities in one adjuvant. Exacto makes multifunctional adjuvants with nonionic surfactant, deposition, drift reduction, water conditioner, and penetrant capabilities. These products can help improve spreading and wetting characteristics to improve the performance of the active ingredient by ensuring uniform surface coverage with reduced bounce and run-off. This is especially important for contact fungicides. Exacto also uses innovative technologies to limit driftable fines by modifying droplet size without pump shear or solution fatigue. These products can also increase penetration through waxy, wetting-resistant cuticles and enhance the permeation of the active ingredient to the mode of action site. These properties are beneficial for improving the effectiveness of systemic fungicides.
Another type of multifunctional is a sticker-spreader, an adjuvant that combines a sticker with a surfactant. Stickers improve contact and adhesion of crop protection products. The most commonly used sticking materials are resins and latex, with resins providing longer-lasting protection as they are more flexible and do not crack as the plant grows. The surfactant provides efficient spreading on the leaf. The sticker can protect the active ingredient against wash-off (figure 1), UV degradation, and wind erosion. This increases the spray’s ability to protect a greater leaf surface area which is important for contact fungicides.
Be sure to read the label of active ingredients to ensure essential adjuvants like surfactants, deposition aids, drift reduction agents, and sticker-spreaders are recommended or not prohibited for use in your fungicide tank mix.
More information:
Fungicide Efficacy
Exacto Activator Adjuvants
Exacto Utility Adjuvants
Resources:
The Wisconsin Bug Guy, PJ Liesch, shares stories of scorpions, emerald ash borers, mosquitos, and other insects in this Cutting-Edge Perspective. As the UW Madison Insect Diagnostic Lab Director, PJ uses his expertise to identify unknown insects to point people in the right direction for pest management.
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