Help with Russet, Cyclamen or Broad Mites

If you think you have the Tomato-Tobacco Mosaic Virus Disease (TMV), but your plants are not responding to treatment, the chances are pretty good that Cyclamen, Russet or Broad mites have entered your space.

Basic characteristics of Tarsonemid mites:  Can be harder to control and identify since they are hidden in flower buds.  Females are usually more abundant than males in the winter months, and they live longer than males.

Host plants include Amaryllis, Antirrhinum, Aralia, Aster novi-belgii, aubergine, Begonia, chrysanthemum, Cyclamen, Dahlia, Fatsia, Fuchsia, Gerbera, Hedera, Narcissus, New Guinea impatiens, Pelargonium, Petunia and Verbena to name a few.

Cyclamen mites:  Steneotarsonemus pallidus

  • Avoids light
  • Prefers high humidity, but can thrive in dry climates (especially in contained crops)
  • Hides in buds and between the calyx and corolla and/or the stamens and ovaries of flowers
  • Females lay two or three eggs per day
    • Eggs are relatively large in comparison to the adults
    • Deposit eggs in moist dark places, in small groups, and require about 11 days to hatch 
    • Eggs have delicate shells, elliptical, 0.1 mm long and smooth
  • Mites molt once
    • New larvae have a wrinkled skin that stretches as they grow
    • Are highly active for about 7 days
    • Enter a quiescent stage for a few days
    • Molt to the adult stage

Broad Mites: Polyphagotarsonemus latus

Copywright Queensland Govt.

Copywright Queensland Govt.

Copywright Queensland Govt.
  • Females lay 30 to 76 eggs on the leaf surface over an 8 to 13 day period.
    • Unmated females lay male eggs
    • Mated females usually lay more female eggs than male eggs
  • Broad mite eggs are:
    • Elliptical
    • Translucent
    • Colorless
    • About 0.08 mm long
    • Covered by 29 to 37 whitish bumps.
  • Young larvae:
    • About 0.2 mm long
    • Whitish
    • Have three pairs of legs
    • Legs have microscopic claws and suction cups
    • Quiescent Stage larva appear immobile and engorged
    • Larvae hatch in 2 or 3 days
    • Larvae are slow moving and do not disperse far
    • After 2 or 3 days the larvae develop into the quiescent larval stage
    • Adult males are attracted to quiescent female larvae, pick them up and carry them to new foliage
  • Adult Broad Mite activity
    Broad Mites On White Fly "hitching a ride" Source: D.E. Walter
    • Mites will frequently "hitch" a ride on White Fly (photo right, click to enlarge) and other insects.
    • Males apparently account for much of the population dispersal by moving the quiescent female larvae to new leaves
    • Males immediately mate with females emerging from the quiescent state.
  • Generation Stage
    • Males live 5 to 9 days
    • Females live 8 to 13 days

Tomato (and Hemp) Russet MiteTomato Russet Mite, @Unknown

  • Adult: very tiny (barely visible with a 10x lens), yellow, wedge-shaped mites with only 2 pairs of legs.
  • EGG: round, clear, almost the same width as adult.
  • Nymph: two stages similar in appearance to adult but somewhat smaller.
  • Generation Time: rapid, 8 days in summer, 15 or so in cool weather.  Adult mites may live for 30+ in ideal conditions.
  • Damage: affected leaves and stems first appear greasy, then turn bronze and may desiccate in hot, dry weather. Lower leaves are first affected. Until recently, Russet mites were rarely a pest except in contained gardening.  However, over the past 5 years, the problem in outdoor cannabis sites has become severe.
Russet Mite Damage
 
Russet Mite Damage

Basic charistics of Eriophyid mites

  • Rust mites attack Alnus, chrysanthemum, Crataegus, Fraxinus, Malus, Prunus, Rhododendron and Robinia.
  • Gall mites attack Abies, Acer, Alnus, Aesculus, Betula, Carpinus, Cytisus, Euonymus, Fagus, Fraxinus, Juglans, Picea, Populus, Prunus, Ribes, Salix, Sambucus, Sorbus, Syringa, Taxus, Tilia, Ulmus and Yucca.
  • The fuchsia gall mite (Aculops fuchsiae) is noteable in that it causes leaves to turn red. Extensive feeding produces extremely distorted foliage.

General Mite Biology

  • Warm, dry weather encourages populations to increase rapidly on host plants outdoors and under protection.
  • Pests tend to congregate in the growing tips, where humidity is high.
  • The bulb scale mite burrows into bulbs during August and September (relies on warm conditions).
  • Mites are spread on the wind, clothing, other insects and animal fur.

Mite Symptoms

  • Tarsonemid mites cause leaves to be puckered, bronzed and distorted. 
  • Eriophyid mites induce leaf galls, felting, leaf rolling and leaf blistering.
  • Affected plants can be stunted.

Mite Treatment: cultural control

  • Attack occurs more often on stressed plants so insure appropriate irrigation, nutrition and climate are provided.
  • Remove and burn any badly infested material.
  • Regularly remove and burn plant debris.
  • Clean and disinfect between crops and/or rotations. 
  • Keep weed populations low to avoid alternative host risks.
  • Avoid frequent use of winter wash and/or oil treatments to encourage natural predator mite populations.

Mite Treatment:  Heat Treatments 

Russet, Cyclamen or Broad mites are very sensitive to heat. They are more difficult to control in winter than in summer due to lower greenhouse temperatures.  

  • Hot Water Treatment:  Soaking infested plants in water held at 111 - 115 degrees F for 15 minutes will destroy these mites without damage to most plants.   (Not recommended for Medical or Hemp growers: use Hot Air Treatment)
  • Hot Air Treatment:  This method can only be used in contained areas (areas or rooms that can be sealed) by raising the air temperature to 115 degrees F for 15 to 20 minutes.  Best results were reported with 100% humidity using (at least) two circulation fans to create some vortex1.  As all eggs may not be terminated using this method, weekly repeat applications may be necessary to achieve desired results.

Note 1:  Fans are usually NOT necessary for small tents, closets, etc. (if installed, use the return air system for re-circulation).   NEVER place fans so they are blowing directly on your plants; they will dehydrate.

Note 2  for Cannabis Growers: efficacy of heat treatment is directly proportional to your canopy density:  as canopy density increases, heat treatments will become less effective as pest insects will simply retreat into new node formations.  Heat treatments are most effective while in veg cycle.

Mite Treatment: Diatomaceous Earth (DE)

Diatomaceous Earth is a very cost effective method for controlling pest insects, but has some limitations:

  • DE is not target specific.  Can not be used with beneficial predator mites in either soil or foliar
  • Looses efficacy in high humidity or becomes wet.
  • Repeated applications can leave undesirable foliar residue

Using Diatomaceous Earth in conjunction with regular Heat Treatments should provide good results.

Mite Treatment:  Natural Bio-Pesticides (OMRI Listed)

  • Beauveria bassiana (Mycotrol -O) is a fungus which infects insects with a disease known as the white muscadine.  When spores of this fungus come in contact with the cuticle (skin) of susceptible insects, they germinate and grow directly through the cuticle to the inner body of their host. The fungus proliferates throughout the insect's body, producing toxins and draining the insect of nutrients, eventually killing it.  
    • Note:  Mycotrol and Botanigard are not specifically listed for Eriophyid or Tarsonemid mites.   In this program it is used primarily for the control of vectors: Thrips, Whitefly, etc. that rapidly transport the pest throughout your garden.  However, scouting at numerous sites has shown high instances of white muscadine infection in both families of mites.
  • Heat-killed Burkholderia spp. strain A396 (VENERATE XC) is an advanced bio-insecticide and features multiple modes of action and is effective against a wide variety of chewing and sucking insects and mites yet easy on beneficial insects and bees. The unique and novel modes of action will complement and improve integrated pest management and insect resistance management programs.
  • Chromobacterium subtsugae (Grandevo) is naturally derived from a newly discovered bacterium, commonly known as Achromacil™, which produces a number of compounds that contribute to the creation of complex modes of action, resulting in a potent biopesticide that is highly active against labeled insects and mites. Control of pests is achieved by unique combinations of repellency, oral toxicity, reduced egg hatch, and reduced fecundity (ability of pest to reproduce). Has also been shown to maintain populations of most beneficial and introduced biological controls. 
  • Isaria fumosorosea (=Paecilomyces fumosoroseus), the active component in PFR-97, is a naturally occurring fungus which infects many insect and mite pests that occur on foliage and other aboveground plant, as well as many soil-dwelling pests.

Mite Treatment: Biological Control (supplementary control with Natural Bio-Pesticides is usually required for Tarsonemid and Eriophyid mites)

Additional info on the use of the above products is available to our clients.  Please call Dave Quillin at Everwood Farm, 503-390-2637

 

 

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