Managing Bacterial Diseases

July 24, 2023

Bacterial diseases, such as bacterial wilt, bacterial canker, bacterial spot, bacteria soft rot, black rot in cole crops, center rot, etc., produce disease symptoms showing on the outer parts of the plant. We know that. What is also important to know is that many times these symptoms are the result of internal vascular system disorders, caused by the bacterial infection, which may have been carried to the plant via insect pests, wind etc.

This vector, or source, is obviously important to control. In the case of bacteria wilt, cucumber beetles carry the bacteria and infect the plants, so we want to control the cucumber beetles if possible. The reality, however, is not that we need to “sterilize” the environment of all bacterial pathogens or sources, but similar to human health, we need to promote health and strong immune systems in plants so that they can resist or even overcome the bacterial infections.

It was already mentioned that bacterial infections often cause disorders in the vascular system. What is that? The vascular system is main “artery” that carries nutrients and water from the soil upward into the plant – so it is obviously a very important piece because without nutrients and water, plants die very quickly.

From experience and published literature, we know that calcium is a foundational nutrient for maintaining a healthy vascular system, along with silica and magnesium and a few others. Bacterial canker is a good example – it is first and foremost a calcium deficiency and it can be resolved if it caught early enough that it has not completely plugged the system yet. Bacterial canker will cause browning inside the vascular system, which can be observed by cutting the stem apart lengthwise. You want to see a healthy color, not brown.

We also know that calcium is important for cell membrane stability. This basically means that calcium, along with silica and boron, builds a stronger plant cell wall that creates an effective armor to protect against disease.

Another important point is the impact of copper and zinc on shutting down bacterial diseases that are already in the plant. Here again we draw on experience and scientific literature: we have seen good success with a foliar application of 2 qt. zinc and 2 qt. copper (applied twice in a row) and shutting down these diseases. This has worked really well for bacterial spot in peppers. Copper is often used in bactericides, but scientific literature states that zinc is among the most toxic of the essential minerals to bacteria. In other words, an adequate level of zinc is one of the effective ways to reduce or prevent bacterial infection.

In summary, bacterial diseases can be managed without bactericides when we earn the right to do so with adequate and balanced nutrition, with calcium as the foundational growth mineral as it should be, silica to harden cells, potassium when needed, and adding zinc and copper as appropriate. Of course, a balance of all minerals is needed, but starting with these essentials.

And although bacterial diseases can technically be categorized into three main types: leaf spot diseases, soft rots, and vascular diseases – from my perspective, it doesn’t really matter that much because the control or treatment ends up being close to the same. The foundational pieces are relevant to most of them, so we should start from there.