Rice Root Aphid
The very phrase “root aphid” often strikes painful fear into the hearts of growers that have heard terrific stories of their pernicious presence. Indeed, the Rice Root Aphid has been for several years now an incredibly difficult pest to exterminate once it establishes in Cannabis cultivation.
While it’s been fairly well known for a much longer period of time especially in grain crops, the oftentimes enthusiastic or furtive movement of Cannabis cuttings between home growers or nurseries meant that transmission of these aphids was rapid and usually went unnoticed by those ignorant or ambivalent towards them. A lack of biosecurity still plagues cultivators of all echelons and scales with poor agricultural infrastructure and research outreach exacerbating large-scale enterprises.
Detection
Rice Root Aphids are most commonly encountered as stowaways in rooted cuttings. Like other aphids, almost all individuals are female, reproduce through livebirth and are born pregnant with what are functionally clones of the mother. At optimal temperature conditions, around 25°C, immature rice root aphids can reach adulthood in as little as 4-5 days, which is extremely quick. This means that a small population of reproductive females that goes unnoticed will quickly become much larger.
They usually can be found on the tips of roots where the substrate and container meet, usually a green body with a reddish abdominal coloration. They have two short tube-like structures called cornicles attached to their abdomen, and while most adults lack wings, it is possible to encounter winged adults even in the substrate.
Rice Root Aphids have a teardrop-shaped body and antennae on the head that curve back across the body, giving them the unique profile for which aphids are known.
Rice Root Aphids found in the foliage may be misconstrued as the common Cannabis Aphids or possibly another species that feeds on Cannabis. Agricultural extension agencies often provide identification services, as do various consultants in the agricultural space.
If their body shape is unfamiliar to the observer, it is prudent to check the roots when an aphid is found in foliage and check photos and videos online from reputable sources to compare. This presentation depicts the Cannabis Aphid, and this presentation depicts the Rice Root Aphid.
Treatment
Because of its unique capacity for subterranean establishment, one of the most successful treatments for Rice Root Aphid is a combination of botanical insecticide and fungal parasite either simultaneously or sequentially. Natural pyrethrins or Neem Tree derivatives are commonly employed with an insect pathogen like Beauveria bassiana or Isaria fumosorosea to the substrate.
The compounds severely interfere with the aphid’s physiology, killing many outright, while the fungal pathogen colonizes the bodies of damaged, moribund and dead individuals which closely congregate. These two methods can also be applied to foliage and even to other pest species, making them a versatile reactionary measure.
Prevention through methodical quarantine protocol is even more effective and should be the primary means of limiting Rice Root Aphid presence. It is highly seductive for growers to trust their sources without verifying incoming plant pest status due to the extra complexity and consternation it entails, but there are major economic and health advantages not only for the individual but also the community at large: stopping the spread of Rice Root Aphid is a biosecurity responsibility everyone is a part of whether we acknowledge it or not.
Fortunately, its infamous reputation may create enough interest in preventative measures that will make the Cannabis community more robust in the face of this common pest.
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