Page 22 - 2017 Griffin Gazette Issue 4
P. 22

By Rick Yates,     fatal. Equally problematic, adult fungus        larvae are not directly damaging to plants.
                              GGSPro Technical   gnats and shoreflies are known to spread
                              Services Manager   root and crown rot diseases in their travels.   Habitat Management
                                                                                                 Habitat modification and sanitation is the
                              Fungus gnats and   Proper identification of fungus gnats and       first line of defense against fungus gnats
                              shoreflies are a   shoreflies is important for control; some       and shoreflies. Fungus gnats lay their eggs
                              nuisance, there's  differences in chemical and biological control  in cracks and crevices in the soil media. In
                              no debating that.  options need to be accounted for. Adult         greenhouses this most often occurs on the
                              They make insect-  fungus gnats are dark, delicate-looking flies,  surface of the soil but can occur in drain
                              leery customers    similar in appearance to mosquitoes, with       holes in the sides and bottom of pots as
                              uncomfortable and  slender legs and long segmented antennae.       well. Constantly moist soil media, and the
                              they leave their   Their wings are clear with a distinctive “Y”    algae it encourages, make a suitable habitat
calling cards (fecal matter) on the foliage      shaped vein. Fungus gnat larvae have a          for fungus gnat larvae. Shoreflies live in
of otherwise beautiful plant material. More      shiny black head and an elongated, whitish-     consistently damp areas with abundant
than one grower has inhaled these tiny           to-clear, legless body. Shorefly adults more    algae. The larval stage feeds on algae and
flies while hard at work in the greenhouse.      closely resemble miniature house flies.         the pupal stage is semi-aquatic, partially
Yuck…. That's not where the list of offenses     Compared to fungus gnats, shoreflies are        submerged in water.
ends. Fungus gnats are a major pest of           stronger fliers and have shorter legs and
greenhouse crops, but don’t often get            antennae. Shoreflies have five distinctive      Moisture management, including improved
the attention they deserve. Direct plant         clear to white spots on their wings. Shorefly   drainage and taking steps to limit algae,
damage occurs through larvae feeding             larvae are also clear to white, but lack a      can pay dividends in terms of creating a
on roots, in stems, and occasionally on          distinct head capsule. The pupal stage is       less favorable habitat for pest development.
foliage, especially leaves in contact with the   dark brown and has an interesting “fork”        Power washing and use of approved
growing media. For seedlings and cuttings        structure on one end. While shorefly adults     cleaners, such as Strip-it Pro, can be used
in propagation, the damage is sometimes          are able to spread plant pathogens, the         to remove organic matter from surfaces
                                                                                                 between crops. After a thorough cleaning,

Table 1:

Product      Active                              MOA   Fungus  Shoreflies Comments
Name(s)      Ingredient                                 Gnats
                                                   15                X IGR, sprench, 21 days of control
Adept        Diflubenzuron                         17      X         X IGR, sprench, vegetable transplants
Citation     Cyromazine                           7C       X         X IGR, sprench, soil surface spray, 21 days,
Distance     Pyriproxyfen                                  X
Fulcrum                                           11A                             Distance- fruiting vegetables
Gnatrol WDG  BT- israelensis                      13       X                      Make 3 applications 1 wk apart
Pylon        Chlorfenapyr                         4A       X                      Soil surface spray only, 7-14 days
Safari       Dinotefuran                                   X         X Soil drench, vegetable transplants

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