Page 18 - Griffin Gazette Issue 1 - 2019
P. 18

Root Aphids:

                                            A Hidden Threat

                                            By Moriah LaChapell, CEA GGSPro Technical Specialist

                                            Root aphids are a widespread pest that can devastate controlled
                                            environment agriculture (CEA) crops, such as lettuce, herbs and
                                            cannabis. Root aphids are difficult to control and detect, since they
                                            feed below the soil line, out of easy sight. Root aphids cause decreased
                                            plant health and crop yield. Scouting for root aphids, selecting the
                                            correct chemical control strategy and preventing introduction of this
                                            pest is key to maintaining plant quality.

                                            UNDERSTANDING ROOT APHIDS

                                            Understanding the life cycle and distinguishing features of root aphids is a critical step
                                            for correct identification. Root aphids vary in color and are similar in size to standard
                                            aphids. Normally, they reproduce by parthenogenesis. This is a fancy way of saying that
                                            root aphid reproduction is entirely asexual: No males are produced and females give
                                            live birth to genetically identical daughter aphids. Periodically, winged aphids develop
                                            and disperse to other plants. These winged adults are more easily seen and can be
                                            trapped on sticky cards and plant structures, such as developing flowers or leaf hairs.
                                            Root aphids may be confused with mealybugs because they're often covered with white
                                            wax. However, they're generally smaller than mealybugs, have cornicles and are pear-
                                            shaped. In comparison, mealybugs lack cornicles and are oval-shaped. Mealybugs
                                            also sometimes have long tail hairs.
                                            Root aphids are often introduced to a facility on incoming plant material. Winged forms
                                            of root aphids can also find their way in through greenhouse vents and open warehouse
                                            doors during warmer months. The best way to prevent root aphids is to isolate all
                                            inbound  plant  material  in  a  quarantine  area  separate  from  the  normal  production
                                            spaces. Plants in quarantine should be heavily scouted, including inspection of the
                                            root systems, and treated for any suspected issues prior to commingling with existing
                                            Root aphids don't spread as rapidly as foliar aphids. They move from plant to plant
                                            via drainage holes in pots or through irrigation water. It's critical to find root aphids
                                            early. If severe root aphid infestations are detected, remove the infested plants. Manage
                                            lighter infestations with the correct insecticides, maintaining tight drench intervals until
                                            the aphids are no longer detected. Keep good scouting records and use preventative
                                            treatments when historic patterns suggest increased risk of infestation.

                                           Image captions
                                           (Top Left) Aphid Cornicles, (Bottom Left) Waxy Residue from Pemphigus Root Aphid Infestation,
        18   |   GRIFFIN GAZETTE 2019      (Bottom Right) Root Aphids Feeding on Plant Roots
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