One of the major problems at this time of the year is combatting the cannabis aphid. And, the last thing you want is a cannabis aphid problem as you go into flower or worse, as you’re in flower. Everyone has a spray program ready and we all endeavor to have a really tight system that allows us to start out clean. Exclusion, sanitation, hygiene, minimal movement between bays are the keys to avoiding cannabis aphids.
Many ways for getting in
But, as we all know, sometimes it doesn’t work. Alison Kutz, of Sound Horticulture, consults with growers across the U.S. on how to reduce, manage, and eliminate pests and pathogens. She talked about one of her customers who has a 12,000 square foot greenhouse and despite all the precautions, he found himself with an infestation.
“Even if someone is paying very close attention, it still takes a few days to discover the problem. Aphids come into a house in every way possible; on clothing, people, plants from another producer that wasn’t quarantined properly, or even from a liner. In this case, it was because the mother plants were in the same room as their propagation plants.”
In some cases, mother plants are kept too long, and they get overcrowded. In other situations, the problem is that the original design of the greenhouse didn’t allow for enough separation and space. It’s understandable that growers would want to hold on to mother plants as long as possible, because it can take up to four months to get the plant to the point where they can get as many cuttings as they want.
Aphids themselves are not the only danger. Even after they’re eradicated, aphids leave weakened plants that are now more susceptible to viruses and other pathogens. Alison offered her suggestions on what to do when you first discover that you have an infestation.
“Once aphids get a foothold, growers can use some sprays on both propagation and stock plants. Cutting dips, actually dipping the cuttings before they’re planted is highly effective, as well as using microbial pesticides. We’ve had great success with microbials. The spore is in the dip and then it sits on the plant waiting for contact with the insect. Within 3-7 days the spores take care of the insects. This technique is especially effective when you can keep the humidity close to 80%.”
She cautioned to check with your local regulations because not all products are registered in all states and the onus is on to be aware of what is legal in your state and what is not.
How to fight aphids
Your problem isn’t necessarily solved after those 3-7 days. After you achieve control, you then have the opportunity to keep those cannabis aphids at bay by releasing one or more predatory beneficial insects to keep them from coming back. “Treatments vary, but in many operations we find great success using a layered approach,” Ms. Kutz offered. “The real work horses can be as simple as releases of Green Lacewing eggs or larvae into the crop to patrol the growing system. We love them!”
Her four “musts” for operating and combatting cannabis aphids are as follows:
- Always do thorough scouting and proper pest I.D. You may think you have a cannabis aphid but in fact, you may actually have a root aphid or some other variety. Good scouting is critical and depending on your budget, the technology exists that can recognize and identify pests within a very short period of time.
- Make sure the environment matches your choice of tools. Not every microbial is appropriate for every environment and many won’t be effective unless you can maintain the humidity that is required.
- Follow through with good record keeping. If you have visual imagery as well as data in your system, your AI will know what to look for next time, it will recognize it, it will alert you and you’ll have a record of how you solved it. It is critical that information is stored and available where everyone can access it because if you’re not there the next time an infestation occurs, what is the next grower going to do?
- Make sure you and your pest control advisor communicate. This one is critical as it’s not enough just to talk frequently, it’s also important that you are both using the same terminology. If not, you’ll get the right advice for the description you’re giving, but you may be giving an incorrect or incomplete description of the problem.
In the end, economics will play a large role in your decision making. Timothy Gibb, in his book Contemporary Insect Diagnostics, added a caveat that every grower considers when contemplating the pest control equation. “Cost is a factor that must enter into the decision to apply pest management options in any system. All pest management efforts cost something. Equipment, personnel time, and insecticides all have a readily calculable cost in dollars.”