The ability to identify and treat various conditions of plants is a critical skill for anyone involved in the production of crops. With early intervention, many of these conditions can be corrected before significant productivity is lost. The key to taking early action is making an early and accurate diagnosis.
Disorders of plants fall into three general categories: insect or disease pests, agronomic issues, and environmental conditions. Despite those very clear separations, certain conditions in one category can mimic conditions in another. This can make diagnosis more difficult and increase the likelihood of an incorrect diagnosis.
One condition that exemplifies this problem is cannabis wind burn. When present on cannabis, it can fool us into thinking it is any of a number of other problems. Let’s dig deeper into how we can figure out that we have a wind burn problem rather than some other issue and find out, “Can plants recover from windburn?”
What is Wind Burn on Cannabis?
Wind burn on cannabis leaves is damage to the foliage of a plant as a result of excess air movement. Through a process called transpiration, plants lose moisture through their leaves much the same way as animals produce sweat. That moisture is replenished with water moving up the stem from the roots. However, if there is too much air movement around the foliage, the rate at which water evaporates from the plant can be faster than the rate at which it’s replaced. When that happens, the plant will exhibit wind burned cannabis leaves.
Any plant is subject to wind burn, but it is more common in plants that are grown indoors. Grow light operations, greenhouses, and high tunnels all utilize fans to circulate air and maintain a consistent temperature. This also helps keep foliage dry, discouraging disease development. Because most cannabis is produced indoors, wind burn is a more common problem with this crop.
What Does Wind Burn Look Like on Cannabis Leaves?
Like many plant issues, cannabis plant wind burn can manifest itself in different ways. One common outcome is the development of what is known as clawed leaves. If you imagine that the leaf is a hand trying to grasp something under it, you have an idea of what clawed leaves look like.
Another common symptom is burnt leaf edges. We don’t want cannabis leaves burning before they’re supposed to, but excess air movement can do exactly that. The leaf margins will take on a brown appearance that clearly indicates a lack of water when cannabis leaf wind burn is present.
Plants can also be stunted by wind burn. The stress that they experience from lack of water interferes with the normal growth they should be producing, and smaller plants are the result.
Wind burn may create spots on leaves that resemble insect or disease damage. Closer examination will reveal that they are only located in areas where fans are significantly impacting the leaves.
The final common symptom of wind burn is drooping leaves. Water is a major factor in what keeps the plant standing up properly, and when water is moving through the stem too fast, the cells don’t keep enough water to maintain strong support.
Mistaking Cannabis Wind Burn for Other Problems
As we mentioned earlier, wind burn can fool us into thinking it’s something else. Here are some examples.
- Nitrogen Toxicity: Too much nitrogen fertilizer causes the leaf to grow faster at the center than at the edges. This can cause clawed leaves. The best way to distinguish between clawing from nitrogen and clawing from wind burn is that nitrogen toxicity will affect the entire plant while wind burn is confined to areas where air movement is concentrated.
- Under watering: Again, a plant that does not have enough water will have generalized wilt and browning as opposed to damage focused near the air paths generated by fans. You can also check soil moisture with your finger. It should be damp, not dry.
- Overwatering: Excess water will also cause wilting as the plant struggles to control the amount of moisture it pulls up from the roots. It will cause generalized symptoms instead of limiting it to the flow path of the fans.
Treatment for Wind Burn on Cannabis Plants
Unlike many plant problems, wind burn can be treated and its damage reversed, giving you back a plant that is nearly as productive as it would have been without damage. Reversing wind burn is a fairly simple process. Properly done, it can restore normal foliar growth and keep you supplied with quality leaf for the consumer.
The first thing you must do is to relocate the fans or, if they are in pots, the plants themselves. Keeping the air from directly impacting leaves is critical to ending wind burn. Depending on moisture and temperature levels in your grow operation, you might also be able to reduce fan velocity, operation time, or fan numbers.
Recovery is as simple as maintaining normal fertility and soil moisture so that the plant can generate healthy tissue again. Prune away the dead and damaged leaves, and consider applying an anti-desiccant that slows the movement of water out of the leaves.
Preventing Wind Burn on Cannabis Plants
We’ve covered much of this in the treatment section, but the same general ideas make sense in preventing wind burn. As you set up your production system, design it with as much detail and research as possible. The more you know about your space, the more accurately you can determine fan needs.
Once again, fan placement is also critical. Lay out your operation so that fans are angled to move air gently across plants instead of hitting them directly. Ensure that fans are properly locked into position so that they do not drift away from their intended direction.