Applying Fertilizer and Fungicide Same Time

Can you tell me if it is safe to apply fungicide with a liquid fertilizer at the same time, in the same application? I have heard from some neighbors that nitrogen will feed the fungus and make it worse if you apply a quick releasing nitrogen source, but i have never thought of applying a fungicide with it at the same time? I am in florida and have a st augustine lawn, i need to add some color with a liquid fert. But i need to knock out the fungus as well, or at least apply some to my lawn as a preventive, would it be safe to apply these at the same time without damage? I am using the contact fungicide.

First and foremost, the most important thing you can do first is to check your ph. As explained in our ph control article, an improper ph will many times prevent grass from using fertilizer properly which in turn can lead to fungus and other turf problems.

Once you know the ph is 6.5-7.0, you should first try to identify just which kind of fungus you have active. Some fungus, like dollar spot, tends to thrive in yards with a low ph and low nitrogen levels. Brown patch tends to thrive in lawns with low ph and high nitrogen. More about this can be found in our lawn fungus control article but for the most part, an abundance of nitrogen should only be a problem if in fact you have done just that: over applied or put out too much fertilizer. Since most any fertilizer label has recommended amounts to be used, it can be determined if you have over applied or not as explained in our fertilizer explained article.

So to answer your question, since only a few lawn fungus problems are associated with too much nitrogen, it’s not likely that this is the reason for the problem. That means you should be able to apply both at the same time with no major problem or consequence. However, if you believe you have overdone the fertilizer applied during the past 2 months, applying the fungicide first and then following up in a 3-5 days with the liquid fertilizer would be the best way to go.

Good luck and green grass to you and yours!!