Of all the pests against which growers have to fight, there is one that is proving itself to be a very tough opponent: Phorodon cannabis, also known as the Cannabis Aphid. Originally spotted only in California many years ago, it has now reached different parts of the world, especially Canada. “One of the theories on how this pest spread says that, a few years ago, there was a cannabis competition in Oregon in 2016, with growers coming from different parts of North America,” Anoo Solomon, Owner and Director of Operations and Education of CannaProtect IPM Solutions, explains. “It was a competition to grow the best clone, so competitors were given clones of the same strain. It is said that within a few months, the competitors noticed this aphid in their crops. Most likely, some clones were infected with aphids, and that’s how it all started. Colorado and California are other States that noted the presence over the last few years as well, so it is hard to pinpoint exactly where they truly started-there has been mention of documentation from 1860 of this pest. In the last two years, it exploded in Canada.”
A tricky pest
The problem with the cannabis aphid is that, as of now, there is no specific solution to fight it. “There is no specialized predator for the cannabis aphid, and everyone is trying to MacGyver a solution for it,” Anoo continues. “At the same time, a big issue is that IPM can be overlooked and deemed not a priority, therefore from a budgetary standpoint minimal funding is issued to build the IPM program, educate the staff and purchase the necessary beneficial insects. It is crucial to understand the fact that putting money into IPM and educating your staff is essential, the initial financial output saves the company money in the long run as they are mitigating crop losses due to pest and pathogen infestations. Less crop loss=more profit. If you take the time to develop a strong IPM/ICM program and fund it properly, the need to cull entire lots can be prevented.”
How to spot it
The trickiest aspect of the cannabis aphid is that it is not easy to spot. “It is different from other common pests, like Two-Spotted Spider Mites or Thrip, for instance,” she points out. “These leave very specific, visual, aesthetic damage. Therefore, if a crop is invaded by mites, growers can see where that is happening.” On the other hand, the cannabis aphid does not. “It leaves no physical damage, as it actually pierces through the stem of the plant into the phloem, which is part of the vascular system that moves nutrients throughout the plant. These aphids inject their stylus into the phloem, and suck out the sap. Ultimately, they excrete a honeydew, which is a sticky, clear, and sweet substance. This creates a perfect breeding environment for sooty mold – and that’s where the real problem starts.” So basically, the plant gets drained of what it needs, it looks droopy, and a little discolored; but other than this, there is no visual damage to the foliage until things are out of control. “To spot it, you have to scout your plants by looking at the stem, the top and underside of the leaves, the flower, the soil.. As the infestation progresses, you would see this black fungal infection on the leaves caused by the honeydew excretion,” Anoo explains. “Another identification factor is a tiny little papery exoskeleton that aphids leave behind as they grow and shed their skin. This is a clear sign of an aphid infestation.”
“Another key factor is ants: they feed on sugary honey dew – they have a symbiotic relationship with aphids as they know they are a producer of a food source. So, if you see ants around your plants, follow the trail and see where they are going.”
Always a chance
However, Anoo believes that even if there is an aphid outbreak, the plants are not necessarily doomed. “My fundamental premise is that there is always a chance to save the crop,” she observes. “Before you decide to destroy it, bring someone skilled in and have them make an assessment. If I am brought in when things don’t look great, that’s when I develop an emergency protocol plan catered to the facility’s cultivation design, which can include the use of chemical, cultural and biological treatments, training up the scouting and production teams while working in those areas to implement that specific protocol. Sanitation and hygiene practices during these outbreaks become an even more important factor in preventing employees from being the vector needed to move the infestation through the facility at an alarming rate.”
According to Anoo, training the staff is extremely important because it would ultimately mitigate pest outbreaks. “Especially when there are people too shy to say, ‘I don’t know what that pest or the damage looks like’. When someone gets hired, and the Boss says, ‘keep an eye out for Botrytis’, it is important to make sure that all employees know what Botrytis looks like and how to handle it properly to not spread the contamination. The staff are looking at the plants constantly, so why not give them extra tools so they know what to look for when it comes to cannabis pathogens?” On top of that, by educating the staff and giving them full knowledge of the facts, they become more aware and it gives them more agency in what is actually happening in the grow. “Instilling the notion of pride in ownership in your teams goes a long way. I hear from Master Growers that, after I taught their staff, they were much more motivated because they had a new and/or better understanding of the intricacies of horticulture and compliance pertaining to cannabis as opposed to feeling frustrated or even not caring from lack of understanding.
The importance of prevention
At the end of the day, the best way to prevent such infestations from happening is to be preventive rather than reactive. “Prevention is how you want to run the show,” Anoo says. “Be prepared, be ready for when it happens, because that is how you can mitigate those issues. Look for the flaw in the flawless. The plant tells you what is wrong by showing it to you, so pay attention to it!”
IPM actually starts before the plant itself is planted. “For instance, you can choose cultivars that are better resistant to certain pathogens – strains are unique in what they are resistant and susceptible to,” Anoo remarks. “There are some genetics that are more susceptible to the cannabis aphid, for instance. We know consumer demand dictates what LP’s are producing but if you can find a way to include more resistant strains in your facility that is a big step toward keeping infestations down.” At the same time, the research on the cannabis aphid is still ongoing, and some promising results are already there. “We are noticing that parasitic wasps are highly effective. These fly over to a juicy aphid, and the wasp injects a live wasp offspring into the living aphid, which becomes the host (this is known as Parasitization). The little wasp offspring feeds on the aphid, mummifying it over time and when they are ready, they literally burst out of the mummified aphid.” Sometimes, nature is more disgusting than a B-series horror movie.