PEST: SPIDER MITES. Rapidly moving yellow, green, or red specks onlower leaf surfaces. It takes a magnifying glass to see them.

SYMPTOMS: Stippling on the undersides of leaves, sometimes also on the buds and flowers, and fine webbing.

TREATMENT: Mites thrive in dust so keep leaves clean. Occasionally wash plants with warm water and liquid detergent to prevent outbreaks. For infested plants, spray leaves, especially the undersides, with insecticidal soap. Treat plants weekly for several weeks to kill mites as they hatch. To avoid introducing mites to your collection. Carefully inspect new plants before bringing them in.

PEST:APHIDS. Small (less than 1/8 inch), slow- moving, soft- bodied, green, yellow, or pink insects that cluster on new growth, flowers, or flower buds. Cymbidiums are especially susceptible.

SYMPTOMS: Buds, flowers, and tender new growth look pitted or stunted. Honeydew, a sticky fluid secreted by the insects, provides a medium for growth of sooty mold, which attracts ants and looks like a black fungus.

TREATMENT: Spray with insecticidal soap, Orthene, diazinon, carbaryl, or malathion. For minor infestations. Simply remove insects by washing plants with warm water and detergent.

PEST MEALYBUGS. Oval to elliptical, cottony-appearing insects with threadlike legs around their horizontally ridged body.

SYMPTOMS: Mealybugs quickly form colonies on leaf and petal undersides, in crevices between leaves, and inside bud sheaths. In time, they develop a cottony coating, hence the nickname "cottony mealybug."

TREATMENT: Physically remove them using a cotton swab dipped in denatured alcohol. Repeat every five to seven days until close inspection shows the plant is clean. Weekly sprays with insecticidal soap, carbaryl. Orthene, deazinon, or malathion are also effective.

PEST:SCALE INSECTS. Hard- shelled, immobilbe, brown, white, or grey bumps attached to leaves, stems, pseudobulbs, and flowers. Several types of scale insects attack orchids, including common brown and Boisduval scales.

SYMPTOMS: Scale insects are elliptical to round bumps, 1/16 to 1/8 inch long. Severe infestations can scar and stunt the plant. Like aphids, scale insects secrete honeydew so sooty mold and ants may tip you off to their presence.

TREATMENT: Remove scales with a swab dipped in denatured alcohol. Inspect plants often, removing scales as you find them. Control severe infestations by spraying with insecticidal soap, Orthene, carbaryl, diazinon, or malathion. Spraying is most effective against the tiny young scales (crawlers), which have no shells and move about the plant or from one plant to another. Spray plants weekly for several weeks to kill crawlers as they hatch.

PEST:SLUGS AND SNAILS.
SYMPTOMS: Chewed leaf and petal margins, holes in buds, slime trails over flowers and other surfaces.

TREATMENT: Remove and destroy these pests. Check under pots and rims; be fiendish about litter removal. Use slug bait for large outbreaks.


DISEASES

1. ROT
DISEASE : BLACK ROT FUNGUS. Phytophthora cactorum or pythium ultimum.
Cattleya and phalaenopsis are especially susceptible, but dendrobium, oncidiums, and vandas can also get disease - as can any orchid left standing in water or in actively decomposing growing medium.

SYMPTOMS: Soft, rotted areas begin on leaves or new growth, then spread into rhizomes and roots and to other leaves if not checked. Infected leaf areas initially are purplish brown, tuning black. The advancing front of the spreading disease is yellowish.

TREATMENT: Remove infected areas,cutting half an inch into healthy tissue. Sterilize the cutting tool in a flame after each cut. Take the plant outside and drench it with a fungicide containing etridiazole or copper sulfate. Isolate water carefully untill the plant recovers.

DISEASE : ROOT- ROT FUNGUS. Fusarium oxysporum cattleyae or
Rhyzoctania solani.

SYMPTOMS: The plant wilts because roots have rotted. Brown, rotten areas may extend from the root into the rhizomes. Leaves become yellowed and twisted.

TREATMENT: Cut off all rotted and discolored rhizomes, sterilizing the blade between cuts. Repot the plant, using new medium and a sterile pot. Take the plant outside and drench it with a fungicide, one containing benomyl if impossible; it can be hard to find. Follow all instructions on the label.

DISEASE : BACTERIAL BROWN SPOT. Pseudomonas cattleyae.
This is a the most common disease of phalaenopsis, but it is known to infect other types of orchids as well.

SYMPTOMS: A sunken, water- soaked lesion develops on the leaf, which eventually turns brown or black. The lesion exudes dark liquid.

TREATMENT: Remove badly infected leaves, sterilizing shear between cuts. Spray the plant with a bactericide. Because the exudate contains bacteria, isolate infeced plants to keep the disease from spreading. Discard plants if their crowns are affected.

2. SPOT
DISEASE : LEAF SPOT FUNGUS. Cercospora, Colletotricum, and other fungi.
SYMPTOMS: Spots start out as yellow areas on the outsides of leaves. As they develop, they become visible on both sides of the leaf and turn purplish brown or black.
TREATMENT: Spray plants using a fungicide containing benomyl, if available. Remove badly damaged leaves. You can leave the ones with a few spots.

3. BLIGHTS
DISEASE : PETAL BLIGHT. Botrytis cinerea.
This is one of the most common diseases in indoor and outdoor gardens. On orchids, it's usually only a problem in humid greenhouses.
SYMPTOMS: Small, circular, pinkish or tan spots appear on sepal or petal after flowers open.
TREATMENT: Cut off and destroy all affected flowers. Increase air circulation and lower humidity, if possible. Clean up any decaying plant matter or litter in the area that may harbor the fungus. Avoid splashinr flowers when watering plants.

4. VIRUSES
DISEASE : VIRUSES. Many viral diseases infect orchids, but diagnosis is difficult.
Symptoms can resemble less seriuos problem.

SYMPTOMS: Black, red, or yellow spots or streaks on leaves. Flowers may have white or brown streaks or mosaic patterns.

TREATMENT: Viruses are incurable; destroy infected plants may carry viruses without symptoms, so sterilize tools in between use on each plants. Space plants so that they don't touch.