Delphy has been receiving increasing reports on rice root aphids found by cannabis growers since the legalization of cannabis cultivation in the United States and other countries. Although other potential pests like thrips, spider mites, broad mites, and cannabis aphids are well-known amongst growers, the prevalence of rice root aphids is becoming a concern.
These pests can cause serious damage to the crop if left untreated, stunting its growth and reducing its yield. Treatment of root aphids can be challenging due to their location in the growing media, and they have been associated with various media types, including soil, aeroponics, coconut coir, and rock wool. It is essential to recognize the signs of infestation early on and know how to manage them. Therefore, Delphy would like to share knowledge on rice root aphids and how to prevent or treat them.
What are rice root aphids?
Rice root aphids, as their name suggests, will colonize the root system of the cannabis plant and feed on the root sap by penetrating the roots with specialized mouthparts. This species is almost identical in appearance to above-ground aphids, however, they can be easily identified if you know what to look for. The wingless stage of rice root aphids is darker green and has shorter legs and antennae.
However, due to its habit of developing in the root zone, it is challenging to identify this pest in its early stages. In other words, it takes a while before growers even become aware that the insect is present inside the production facility. Growers typically discover dead winged adults trapped on plant hairs at the upper leaf surface as the first sign of a rice root aphid infestation.
Figure 1 Wingless stage of rice root aphid (Left image, retrieved from: https://mlachapell.com/rice-root-aphid-management-and-life-cycle) Winged stage of rice root aphids (Right image, retrieved from Whitney Cranshaw, Volume 11, Issue 1, 2020, 15, https://doi.org/10.1093/jipm/pmaa008)
For most of its life cycle, the rice root aphid is in the root zone, and when the population reaches high enough levels, winged adults will form and climb up and fly to colonize new plants. Their reproduction is entirely asexual meaning no males are produced and females give live birth to genetically identical daughter aphids. They develop quite rapidly and are able to mature within 10 days. The adults can live for approximately one month and can produce several daughters each day. Furthermore, the climate conditions that are ideal for producing cannabis indoors allow rice root aphids to thrive and populations can even double every 1.6 days.
Damage caused by rice root aphids does not seem to produce any unique symptoms but rather a generalized decline and reduced rate of growth of heavily infested plants. It’s important to regularly scout for pests to be able to tackle the problem early on. Yellow sticky traps across your cultivation area or Horiver discs around the base of the stem can capture aphids on the move, making it easier to spot an infestation.
Prevention is key
To establish a pest-free growth environment, it is essential to prioritize hygiene at all stages of the cultivation process. This involves maintaining cleanliness during the sourcing of plant material, growth media, pots, and ensuring a clean environment after each cycle.
Plant material, such as seeds, cuttings, or clones, should be acquired from a reliable certified supplier and undergo a rigorous inspection and quarantine period before entering the grow facility. Cleanliness should be maintained by removing plant debris and sterilizing all surfaces, equipment, tools, floors, and fans after each grow cycle.
In addition, a strict order-of-entry policy should be enforced for employees and guests, and access to specific sections within the grow facility should be appropriately regulated. Educating crop workers on the risks associated with introducing pests from outside and transferring pests from one area to another is also important.
To control rice root aphids or any pest for that matter, chemical pesticides are not advised since they may end up in the harvested flowers, harm beneficial insect life in your grow area, or leak out into the surrounding environment.
However, there are some biological options available to growers to combat an infestation of rice root aphids. Among these options is the application of Beauvaria bassania, an entomopathogenic fungus, that can be applied to the root zone. This is usually applied by drenching the roots of plants growing in soil-based media with the fungi solution before transplanting them into bigger pots. Some growers use Atheta coriaria (predatory beetle) or Stratiolaelaps scimitus (predatory mite), however, hard data on the efficacy of these insects in suppressing rice root aphids are still lacking.
It all really depends on your cultivation system. If you’re an organic or conventional grower, greenhouse or indoor, which growing media you use, etc. All these aspects ultimately determine your best option for integrated pest management.
If you suspect you have a problem with rice root aphids or any other pest, it is important to act quickly. Delphy can provide you with the knowledge and expertise you need to identify, prevent, and treat pests in your cannabis grow operation.
For more information:
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