NORTH OF ENGLAND ORCHID SOCIETY

Orchid Problems and Pests...

 
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Free Orchid shows.

New members are always welcome, but our normal monthly shows are free to all, come along and take a look at your local orchid society at the venue below

September.
September 13th. Saint Peters Assembly Rooms, Hale, Cheshire.
See our orchid show page

Orchid Paintings


Orchid Paintings

historical paintings

 The above are just two images of the many Historical Paintings of Orchids awarded at our shows from the turn of the century through to the Second World War.

see more images ?

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Next Annual Show

Summer 2015

Each year we hold one of the largest orchid shows to be seen in the North of England, in the wonderful surroundings of Historic Tatton Park Cheshire.

With many traders selling orchids and supported by other orchid societies, its not one to missed.

 For more details visit our special annual show pages.

Orchid Problems and Cures?

Pests

Spots and Diseases

Orchid Viruses

Symptoms

Treatment

see books on orchid pests and diseases priced in UK pounds

 
see books on orchid pests and diseases priced USD


PESTS AND PROBLEMS  
(or one or two common ones in the U.K. at least)

PESTS.
Orchids generally do not suffer from the usual plethora of ailments which affect many of our favorite garden plants, this is for two reasons, firstly many of the species and hybrids we grow are alien to our local atmosphere, and consequently also alien to many pests and diseases we find outdoors, and the second one is that because of the fact that we grow them mainly indoors they are not exposed to the problem in the first place.
Unfortunately, when a problem occurs it can be difficult to eradicate once is gains a foothold.

Here are a few, in no particular order:-

Slugs, even if you think you haven't got any problem with these night-time assassins, you should always be vigilant for their silvery trails, sprinkle at regular intervals with a good slug liquid, and if you feel adventurous, take a torch-light trip into the growing area after dark, a good well aimed boot is something they have not grown immune to.

Weevils, when you wonder why there is suddenly a hole in one of your best grown leaves, or chunks missing out of its margin, then most likely you have weevils, arm yourself with a bottle of something suitable from the garden centre and follow the instructions.
Its no use spraying the once, you must have strict regime of spraying every 5 days or so over a period of three weeks to eradicate most pests and their eggs as they hatch.

Common Scale.
There are two types of scale which you are likely to encounter when growing orchids;- The first one attacks Phalaenopsis in particular, and can migrate to most other soft leaved plants, look on the underside of the leaves for these hard brown limpet like creatures, if you have only one or two, wipe them off with a cloth soaked in methylated spirits, or resort to a systemic insecticide regime as mentioned in the above paragraph, systemic insecticides act by being absorbed into the plant tissue, effectively making the plant poisonous to its attacker, but they should be used with care, do not exceed the stated dosage to avoid damaging the plant.
The other can be very nasty, and primarily has a taste for Cattleyas and their cousins, but can adapt to devouring other orchids such as Vanda's, this is:-

Boisduval scale.
A very fancy name for a real horror, you may notice flat round scales on the underside of the leaves, which if left unattended will produce a whole shipment of what appears at first to be a white fungus or mealybug, these are the nymphs by the thousand, and they are setting off to desiccate the rest of you collection.

The trouble we have in the UK is that it is a tropical insect, and many of our pesticides do not treat the problem, one we have found to be of use recently is Doff, you may have to search around to find it, it is very effective against this type of scale, and several other pests as well, you will probably have to give the plant a good cleaning after a couple of weeks or so for aesthetics. Prior to treatment, take an old toothbrush, dipped in methylated spirits, and having removed any old sheaths ( papery coverings from around the pseudobulbs), scrub gently to remove the majority of the adults.

Mealybug
Usually appears as a cotton wool ball around leaf axils, or inside the sheaths of new shoots, the above fungicide pesticide soon sees them off, but again if its very localized, then methylated spirits on a cotton bud sees them off wonderfully.

Thrips, greenfly, blackfly, spider mite.
They all find a niche somewhere, the latter is another difficult customer to deal with, and in addition to spraying, it is a good idea to wipe the leaves and stems of infected plants with a methylated spirit soaked cloth, every few days if necessary to kill the eggs.

SPOTS AND DISEASES.
Orchids can fall foul of leaf rot, mildew, botrytis and many other pathogens, by and large, providing there is a good air movement around the plant, and that by nightfall the leaves are fairly dry, then fungal infections should not be a problem, and correction of the bad condition, along with a fungal spray (check with the garden centre that it is safe for orchids) should do the trick, a fast fix for a localized leaf infection is to dust a little cinnamon onto the infected area ! It is very difficult if you have a plant suffering from a virus disease to identify which particular type it is, and most likely a useless exercise anyway, as viruses are almost impossible to cure, thankfully, providing you are hygienic around the growing area, and that any tools used on the plants are thoroughly sterilized after use between different plants, you should not encounter this type of problem. Return to top of page

SYMPTOMS.

POSSIBLE CAUSE

Irregular markings on leaves, discolored or uneven patches on flowers

possible viral infection

Uneven pieces removed from leaf border

weevils

Un-natural silvery underside to leaves

spider mite

Silvery trails on plants and benches

slugs or snails

Holes in leaves or flower stems or flowers

slugs or snails

Dark mildew on leaves, hard limpet creatures underside of leaves

common scale

Cotton wool type of stuff ( brownish creature inside of mass)

mealybug

Flat scales on mainly underside of leaves and or tiny white fluffy masses

boisduval scale

Depressed dark spots possibly with lighter ring round them

fungal infection

Limp flaccid leaves on Phalaenopsis etc.

root problems

Dark brown or whitened patches on leaf

sunburn

Yellow or very light green leaves but plant flowers

too much light

Dark green leaves but plant does not flower

too little light

Flower buds develop then turn yellow and drop off

shock

Leaf tips turn brown

over feeding

Honey dew on leaves

greenfly

Plant falls out of pot

earthquake

ORCHID VIRUSES  

Firstly its important to remember that what may appear to be a virus could be just a symptom of bad culture.

Viruses are the most widespread disease problems affecting orchids and fortunately most of them are rare and in many cases hardly cause symptoms.  Only a few orchid viruses are common and can cause problems, the two most important of these are Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV).  These viruses are found throughout the world and have a wide host range, affecting many orchid genera.

CymMV virus infection causes leaves to show a mosaic pattern of light and dark green areas, or black/brown necrotic spots often appearing as a line with sunken areas on both sides, Petals may develop lines of necrotic spots, however floral symptoms may be delayed up to 10 days after opening, so healthy appearing flowers may be sold on.

ORSV virus infection causes necrotic spots, sunken areas, chlorotic streaks, line patterns and ring spots on leaves and stems.  Cattleyas and their hybrids display colour breaks with irregular streaks of pigmentation.  Floral symptoms render the plant valueless, while the leaf symptoms make it unattractive as a house plant. Both viruses are easily transmitted from plant to plant by contaminated cutting tools, work surfaces, used pots and hands.  Therefore, if an infected plant is added to a collection, the virus can easily be spread to healthy plants through propagation and other normal day-to-day plant care practices.

Both these viruses which affect orchids are very stable and lose their infectivity very slowly, so sap from an infected plant that has dried onto tools, pots or benching provides an excellent source of infection.  They can remain infectious for weeks or longer under the right conditions.  The greatest risk of spread is via vegetative propagation from an infected mother plant and is the easiest way to find yourself with more virus infected plants.  If plants to be meristemmed are displaying suspicious symptoms, they should always be tested for viral infection first, before introduction to a greenhouse.

TREATMENT FOR PESTS AND PROBLEMS

Should be carried out giving due consideration to the instructions for use and safety provided by the manufacturers of the control substances we list below; solutions which we have used and found to be satisfactory for ourselves, the decision to try one or more of these in your environment must be yours and made under your own responsibility.

It is always a good idea to try and remove as many of the pests and their eggs a possible before applying insecticides, pure methylated spirits (not surgical spirit) is excellent for this purpose, apply a little on a cloth and wipe both sides of the leaves, for the less aggressive pests this alone can be a cure in itself.

Don't expect a one off cure, several applications given over a period of three weeks at five day intervals may be needed. do not use more  than one insecticide at a course of treatment or you may build up resistance to it.

One fairly general and quite successful insect killer for orchids is Provado Ultimate Bug Killer, in the spray can, rather than as a liquid, for some reason this appears to have a terminal effect on many orchid pests which do not succumb readily to the liquid variety and offers better control of spider mite; it is safe to use on most house plants, providing you follow the instructions, and once again, several applications given at 5 days intervals is recommended for the best success rates.
One home made cure can be produced in the kitchen if you want a non toxic insecticide, here is the recipe for you to try at your own risk :- Six heaped teaspoons of ascorbic acid (vitamin C.) three teaspoon of plant friendly detergent (non ionic) and a pint of water, spray onto aphids and suchlike, the mixture will kill any insects which absorb oxygen through their skin, but not their eggs. As prevention is always better than a cure, treat new plants with respect, quarantine them if possible, try not to let intake fans suck air in from anywhere near a flower border or hedge, and always be prepared to sacrifice a "well infected" plant for the sake of the rest. It will not work on all pests Return to top of page

 

PROBLEM

TREATMENT

Viral infections Virused plants have no place in the greenhouse, but unless the virus spoils the visual quality of the plant, a single isolated one may be used as a houseplant. whilst viruses cannot be treated many plants first thought to be virused will test negative.
Weevils Bifenthrin, Thiacloprid - in the UK try Provado Vine Weevil Killer
Spider mites (see below) Bifenthrin, Pirimiphos methyl,, Malathion Rotenone- long term increase humidity it is difficult to eradicate these pests without a specific insecticide, most of which are currently banned for home use, try anything that says it will cure, but be prepared for a long battle, and keep up with treatment, to get newly hatched mites as they appear. in the uk Try Bio Liquid Derris Plus or Bug Free
Slugs and snails Metaldehyde, Methiocarb, Aluminiumsulphate -
Common scale You should find a suitable insecticide at you local garden centre or use, Insecticidal soap to wash the pests off.
Boisduval scale Imidacloprid and Methiocarb, Sulphur and fatty acid mixture in the UK you could try Provado Ultimate Bug Killer but it must be the in the can formula ( see above ad.) or Doff
Mealybug Imidacloprid and Methiocarb, Malathion, Insecticidal soap, Sulphur/fatty acids. In the UK try Provado Bug Killer
Fungal infections Sulphur, Cinnamon powder
Root problems Remove dead roots, and repot if in time, usually due to overwatering
Sunburn re-site orchid giving correct amount of shading
Shock identify cause, (could be severe temperature light or humidity change) and correct
Overfeeding thoroughly flush pot through with clean water, repot if necessary
Greenfly Sulphur/fatty acids, insecticidal soap, Dimethoate, Malathion in the UK try Provado Bug Killer or Doff
Thrips Imidacloprid and Methiocarb, in the UK try Provado Ultimate Bug Killer

Spider mites like dry conditions, and can be difficult to eradicate, if you only have an infestation on one plant, make life unpleasant for them, water the plant, and place it in a clear plastic bag, blow the bag up with your mouth and tie off, leave the plant there for a few days or so as long as it does not appear stressed, the humidity which will build up inside the bag will create a hostile environment for the mites, but of course their eggs may survive, and you may have to repeat the several times to eradicate them.

 

Images below of some of the least recognised pests courtesy of www.insectimages.org

Aphid Nymph - photographer Whitney Cranshaw, Colorado State University Boisduval Scale Mealybug - States National Collection of Scale Insects Photographs Archive, USDA ARS

Aphid (adults have wings)

Boisduval Scale- Male Nymphs

Mealybug

Two spot red spider mite

false spider mite - Photographer Whitney Cranshaw, Colorado State University

Scale insect

two spotted spider mite

NOT VISIBLE TO THE NAKED EYE

false spider mite

NOT VISIBLE TO THE NAKED EYE

Adult Scale Insect

(ALSO AVAILABLE IN BROWN)

 

thrips - Photographer: E. Bradford Walker, Vermont Department of Forests, Parks and Recreation

 
 

thrips - actual size 1 mm

VARIED COLOURS

 

 

 

 
Welcome
Welcome
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One of our Gold Medal RHS Displays

For many years we created Gold Medal Winning Displays at the RHS Show Tatton Park....

Large Annual Orchid Show

Each year our Annual Show brings one of the largest orchid events to the North of England, Held in the Tennents Hall at Tatton Park....

World's Oldest Orchid Society?

Established in 1897, we have been giving awards to orchids since the turn of the Century, this is an image of one of the early orchid paintings, from which our badge is derived....

Catesatum pilateum

There are over 35000 species of orchid, here is one of the more unusual from the tropics, often seen at our monthly shows....

Laelia purpurata

This showy species makes a change from the usual Phalaenopsis Orchids found in the supermarkets; many specialist growers attend our shows....

Anguloa

Another species of orchid prized by the enthusiastic grower, these plants can be quite large, and are very showy...

Ophrys - The Bee Orchid

At each of our monthly shows, you will see (at the right time of the year) some fine specimens of terrestrial orchids from the temperate zones....

Dendrobium thrysiflorum

For sheer flower power you cannot beat some of the orchid species which may carry over a thousand blooms....

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