Is it Wise to Mix Fertilizers with Fungicides?

Farmers often use fungicides to protect their crops from fungal diseases. A common question that arises is whether it's okay to mix fertilizers like urea, zinc, or other NPK grades with these fungicides. Experts advise against this practice, and there are several important reasons why.

When Do Fungal Diseases Appear and How to Spot Them?

Fungal diseases typically thrive in conditions of high humidity, wet weather, and low temperatures. They manifest on leaves, stems, and fruits with distinct symptoms.

Leaf Spots: You'll often see white, brown, or black spots on the leaves. These spots can look powdery or cottony.

Yellowing of Leaves: After spots appear, the leaves may gradually turn yellow and eventually fall off.

Stunted Growth: Fungi absorb the plant's nutrients, which hinders its growth and makes it weak.

Differentiating Fungal Diseases from Bacterial Diseases and Nutrient Deficiencies

It's easy to confuse fungal disease symptoms with those of bacterial infections or nutrient deficiencies, but there are key differences:

Fungal vs. Bacterial Diseases:

Fungal diseases usually cause dry, circular spots on leaves, whereas bacterial diseases lead to angular, water-soaked spots.

Bacterial infections often produce a foul odor.

Fungal Diseases vs. Nutrient Deficiencies:

Fungal symptoms start in one area and spread gradually across the plant.

Nutrient deficiencies, however, cause symptoms to appear uniformly across the entire plant. For example, a nitrogen deficiency causes all lower leaves to turn yellow at once, while a fungal disease causes yellowing in patches or spots.

Why You Shouldn't Mix Fertilizers with Fungicides

Mixing fungicides with fertilizers can be harmful to your crops for several reasons:

Chemical Reaction: When these chemicals are combined, they react and their efficacy is reduced. This reaction weakens the fungicide's ability to kill the fungus, meaning the disease might not be fully eradicated.

Feeding the Pathogen: Even if a chemical reaction doesn't occur, the nutrients you add (like urea) can end up feeding the very fungus you're trying to eliminate. You're essentially giving a food source to the disease while simultaneously trying to kill it.

Plant Weakness: A diseased plant is already weak and cannot absorb fertilizers effectively. This leads to wasted nutrients and less than optimal results.

Therefore, when spraying a fungicide, you should never mix it with any fertilizer, whether it's urea, zinc, or any NPK grade. First, spray only the fungicide to eliminate the disease. Once the plant is healthy, then you can apply fertilizers. This approach will keep your crops healthy and prevent unnecessary costs.