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Cyclamen mite

Tarsonemus pallidus is the mite most often found on cyclamen.

Its reproductive cycle is extremely fast, especially in summer, when glasshouse infestations do most damage.

Because of its physiological requirements it stays hidden in the most damp parts of the plant. There is no real symptom to be seen on the outside at first, and the pest develops quickly right from when the plants are young.

Chemical treatment must be given regularly and as a precaution.

There are prospects for biological control.

Summary

  • Introduction
  • The species that do the worst damage on cyclamen
  • Life cycle and body features of these mites (T. pallidus)
  • Environmental requirements of cyclamen mites
  • Damage found on cyclamen
  • How cyclamen mites spread
  • Another mite that attacks cyclamen:
  • Prevention
  • Biological control
  • Chemical control

> Introduction

Cyclamen mites are tiny mites, less than 0.5 mm long, of the family Tarsonemidae: a number of species are generally referred to as ‘cyclamen mites’. They are some of the cyclamen’s worst pests.

> The species that do the worst damage on cyclamen

The parasites most often met with on cyclamen, and the ones that do most harm, are Tarsonemus pallidus Banks (Steneotarsonemus pallidus Banks), also known as Phytonemus pallidus, and Polypha Tarsonemus latus, larger and more mobile.

> Life cycle and body features of these mites (T. pallidus)

Cyclamen mites are extremely small, scarcely visible to the naked eye. The adults are oval in shape, from 0.2 mm long to about 0.25 mm. They look like small spiders. The females are a little larger than the males, and their colour varies with the stage of development, from yellow to brown at maturity. They have 4 pairs of legs.

The males are squat, with characteristic hind legs ending in a kind of hook. The sexes are very different in appearance.

Cyclamen mites hibernate in conditions which do not suit the adult female, in plant matter and never in the soil.

These females produce small eggs of a glassy white, about 100µ across, from April onwards.

A female can lay some thirty eggs in her lifetime; each hatches into a young larva from 4 to 8 days after laying.

The young larvae are milky white, translucent, and segmented. They moult once.

The larvae move towards the young buds and young leaves, before going into the nymph state after 4 to 10 days.

Here, sheltered from wind and weather, generations may succeed each other unnoticed on the outside.

The nymphs are around 0.25 mm long, white, motionless, generally heaped together with eggs.

In 8 to 10 days, the nymphs turn into adults. Males only appear in the summer months, but the females can lay either fertilised or non-fertilised eggs. To a great extent, reproduction is parthenogenetic.

In summer the development cycle is extremely fast. A generation may go from larva to adult in as little as 10 days: the result is a high number of generations in a year (8 to 10). In a glasshouse many generations will overlap. It is in summer also that cyclamen mite infestations cause most damage in the glasshouse.

An adult may live 10 to 30 days.

> Environmental requirements of cyclamen mites

Cyclamen mites require a relative humidity of around 80% to 100% and a temperature of about 15ºC (59ºF) to 22ºC (72ºF). At all development stages they shun the light; they are not found on the parts of the plant exposed to sunlight or warmth, but shut themselves up inside flower buds, flowers and young leaves, to stop their bodies drying out. They have a soft outside, since their exoskeleton contains little chitin. Infestation can occur, therefore, with no outwardly visible sign.

When relative humidity is below 70% they die.

> Damage found on cyclamen

In glasshouses this pest is active all year round. Both larvae and adults feed and cause damage.

Choosing the underside of leaves, the mites pierce the plant tissue; they empty the surface layers of their content, and also secrete certain substances which throw the plant cells’ growth regulation out of order. The result is chestnut-brown, corky growth on the underside of the leaves.

The most typical features of cyclamen mite attack are the curling up of the young leaf edges, which become crisper and harden; flowers become crisper, develop asymmetrically and have difficulty opening; they barely rise out of the foliage.

  • cyclamen mite attack produces a deformation of the leaf stalks and leaves. The leaves then turn dark green in severe cases.
  • flower infestation produces deformation of the flower stalk; buds fail to develop but become wizened and dry. Blooms do not last, the petals fall prematurely; flowers are misshapen and may be discoloured, with a kind of black marbling and oily patches. One general result of this infestation is that the flowers often open beneath the foliage. The piercing and added poisoning by saliva lead to a cessation of growth.

Essentially it is the plant’s young parts, and the younger plants, which are susceptible, since the mites can only insert their piercing and sucking mouth parts into soft tissue. It is at the larval stage that they do the greatest damage.

Damage on leave caused by Polyphagotarsonemus latus

Flower buds attacked by Polyphagotarsonemus latus

Flower petals deformed by Polyphagotarsonemus latus

> How cyclamen mites spread

The adult mite moves around on its legs, but only to a limited extent. Attacks are therefore localised. Adults are happy to stay on the flower bud, flower, or leaf where they emerged, and only migrate in cases of massive overpopulation.

Transfer from one plant to another is done by contact and as a result of the various human operations on the cyclamen in the course of tending them. Cyclamen mites may also be spread by wind and draughts.

> Another mite that attacks cyclamen:

Tarsonemus latus (Polyphagotarsonemus latus)

Originating in the tropics and subtropics, this species is now well established in Europe, and infests cyclamen. It is yellowish or greenish and the females are between 0.14 mm and 0.24 mm, the males 0.11 mm and 0.17 mm. They make their home on the underside of leaves and invade the buds while they are still closed. Infested new growth of the plant is wizened and discoloured, shiny, crumbly and misshapen. The flowers are deformed and buds may fall off. Bad attacks may kill the plant.

> Prevention

Cyclamen mites may appear at any stage of the plant cycle, from seedlings all the way to flowering plants. Regular inspection of the plants will let the grower be quick in getting rid of any that are thought to be under attack.

As precautionary measures, one can:

  • reduce humidity to 60%-75%, to keep the environment inhospitable to the attacking mites
  • keep temperatures between 20ºC (68ºF) and 25ºC (78ºF)
  • avoid too much nitrogenous or potassium manure, which encourages fertilisation of the mites and prolongs their life.

> Biological control

Biological control of mite infestation can be done with the help of predator mites. These predators are often smaller than their prey. They do no harm to the plant.

There are a number of predator mites which feed on these pests, including Phytoseiulus persimilis (Phytoseiulus System, Phytoseiulus T. system, Phyto-line p, Spidex, Spidex Plus) and Amblyseius californicus (Californicus system, Ambly-line cal, Spical). However, they mainly prey on other mites, such as Tetranychus sp, and not on Tarsonemus pallidus or Polyphagotarsonemus latus.

> Chemical control

Under glass there is no avoiding the preventive use of specific anti-mite chemicals: infestations are seldom all of one kind.

The constant development of the regulations and homologations of phytosanitary treatment products, and the differences in regulations according to each country make it impossible for us to include updated information on homologations. Each producer will have to contact his local plant protection bureau to obtain the latest updates concerning the regulations and use of phytosanitary products. We strongly advise testing beforehand on a plant sample in order to measure the chemical’s activity (establishing the dose) and any effect on the plant (plant poisoning).

Caution

This advice sheet is based on the methods used at the SCEA at Montourey (Fréjus, France). These procedures may need some modification to adapt them to other climatic situations. Before starting to grow cyclamen there needs to be a review of precautions against pests and diseases. We must point out that our advice and suggestions are offered for information purposes and therefore cannot include any guarantee of specific results; it is a good idea to carry out trials beforehand.

Tarsonemus pallidus is the mite most often found on cyclamen. Its reproductive cycle is extremely fast, especially in summer, when glasshouse infestations do…

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01/13/2016

Broad, Cyclamen, and Russet Mites: Cannabis – The New Scourge

Question from my Online Compatriot ZEET:

I’ve seen a few posts about broad mites from you and don’t know exactly what you are talking about. I was at the cup here in MI too and I read that you had seen a bunch of plants that had them. I got a few clones from there and one in particular has a odd leaf thing going on. Not sure that it is broad mites but I don’t know exactly what to look for.

Are they a systemic sort of thing? like will the clones of clones have them?
Is there a good way that you know to get rid of them or to manage them?

This is a VERY difficult class of insect to control, for many reasons. Most growers are powerless in the face of an infestation.

The photo to the right is a leaf damaged by the insects. Note the leaf-stem, powdery. Reddish, dry looking. The edges of the leaf curling up.

One must act preventatively, which is more likely to allow for continued control from the BM’s. Especially, if One accepts clones and plants from others’ gardens. Or if the specimens are moved from outdoors into an indoors growing scene (which is never recommended).

In addition, one must be aggressive in tossing away varieties that are prone to attack. Some strains are more able to withstand the bugs. OR, the BM;s are more aggressive with some strains. This occurs with Spider Mites, although they act in completely different ways, and do absolutely different damage.

There is a thread called “Broad Mites?” on the venerable forum at www.icmag.com which has tons of information. Mostly in the “vegging state,” are the Bugs easier to see, as well as their damage. In flower, some folks wonder why the yield was one-haldf of normal, but it can still be possible to pull off a crop. That is part of the problem. People don’t realize they have the insects in the garden, until it is too late. In flower, the pistils are half as long as usual. Almost as if they were burned, or oversprayed. Sometimes they brown up at the tips. The buds are not as juicy as normal, and can yield absolute zero on some strains. Especially purple strains.

It is far easier to see the eggs than the bugs. Note, the singular one in the photo. They exhibit a pattern that appears to be a grid, in most scopes. The following picture is under extreme magnification. One needs at least a 60x scope or jeweler’s loupe to see anything. The Broad Mites are 1/150 of an inch. Sounds not so small, but they are. Once one knows what ones’ looking for, it is possible to BARELY see the bugs. But the presence of the eggs, and the leaf-curling and ‘stipling’ are symptoms of the BMs passing which are enough to go on. The photo of the green leaf, with the presence of Mites shows the ‘ leaf-stipling’ that I refer to.

Popular “It” varieties are the most likely to have BMs, or cyclamen/russet mites. Often, simply because these strains are being shared more than others. All the same results pretty much in terms of effect. The bugs chew on mostly the bottoms of the leaves, and their saliva poisons the plant. Leaves twist, and do odd things. The edges of the fingers in the leaves rollup like taco shells. They appear dry, or crispy on the sides which curl up. Discoloration follows the edges of the leaves, and the central point where the fingers meet is often reddish. This is a part of the leaf structure where the bugs usually congregate, although they often hang out on the leaves as well.

Here is an example of highly-developed infestation.

Whiteflies are necessary to control as well. As unlikely as it sounds, although the bugs are able to walk to new parts of the plants – where they take the Females to new ‘territory’ in order to mate, the Mites are often able to ‘hitch a ride’ on the legs of the flies. As in this extremely magnified photo that is appaling.

New growth is the favorite food of these bastards. You will notice it there first, and in veg. The small new leaves turn yellowish, and then the dry, and crispiness I describe above can occur. Or the new growth seems to stop and shrivel up. Also, other leaves will twist. This is NOT Tobacco Mosaic Disease. TMD is very rare, and the Broad Mites are unfortunately, not.

The almost-microscopic pests can wipe out a veg room. After many years, quite a few experienced growers have been thwarted by the presence of these seemingly new bugs on the scene.

There are even those who maintain that the infestation was a conspiracy. One could ‘seed’ the clones at one of the premier dispensaries in Northern California with BMs, and the bugs would thus be transferred throughout the whole Medical Cannabis Community in very short order.

When the Bugs attack, many people do not notice the problem until it is far past too late. That is a characteristic of the Broad/Cyclamen/Russet Mites that makes them so hard to control. One seems to need to live through an infestation to really learn what to look for. Unfortunately, it is often essential to start over with completely new equipment, and maybe change locations.

Heat treatments for the plants are the most effective way to treat plants. 110 degrees held at 20 to 30 minutes will allow all the eggs and bugs to be eradicated. Keeping that temperature is harder than is seems.

Spray solutions also work. Avid alternated with Forbid every 8 days or so. Reverse Osmosis water. Some surfactant, a couple drops dishsoap, “coco-wet” is a wetting agent made for plants and is best.

Question from my Online Compatriot ZEET: I’ve seen a few posts about broad mites from you and don’t know exactly what you are talking about. I was at the cup here in MI too and I read that you had seen a bunch of plants that had them. I got a few clones from there and one in particular has a odd leaf thing going on. Not sure that it is broad mites but I don’t know exactly what to look for. Are they a systemic sort of thing? like will the clones of clones have them? Is there a…