Indoor Plants (Pests and Diseases)

Indoor Plants are subject to attack by surprisingly huge number of pests & diseases, not quite as many as outdoor plants, but more than enough for most plant owners.

Most Pests & Diseases arrive with new plants, so always inspect any potential purchase thoroughly before putting it with your existing houseplants.

How to use chemicals?

Modern pesticides are usually effective, and when used correctly, they are harmless to plants, pets, & people. However they often contain potentially damaging substances, so take care when using them.

Choose the right Product for the Problem

Read the Label & follow the instructions

Use the correct Dose

Spray outside, if possible, in sheltered positions

Spray Plants inside a large plastic bag, when using aerosol spray, & leave them for 20 minutes

Remove pets (especially fish) from the room where treatment is taking place

Keep pesticides away from children & animals

Houseplant Pests

APHIDS

There are many different species of aphide, some are known as greenflies, but they are all treated in the same way.

Aphides feed by sucking sap from plants, weaking it & sometimes spreading virus diseases. They execrete a a sticky honeydew which is a nuisance when it drop on furniture. In severe attacks, it also encourage the growth of powdery black sooty mold on the leaves of the plants

Infestations are usually concentrated on soft young growing shoots & around flower buds, and aphids may be present in such numbers that they cause distorted growth

Nonchemical control:

Caught at early stage, colonies can be removed by pinching off affected shoots or gently washing off aphids with tepid water, alternatively use safer, s soap or oil spray

Suitable insecticides:

Use selective insecticides such as pyrethrum or pryrethrin which have a short residual life.

CATERPILLARS

Caterpillars are a larval stage of various insects,& they have voracious appetites.

One of the more common caterpillars found on indoor plants is that of the variegated cut worm that feeds on plants such as carnations. While they feed, these small Yellow –green grubs climb the plants, chewing the young buds & leaves .

Nonchemical control:

Pick off individual caterpillar or ay infested shoots

Suitable Insecticides:

Apply diazinon to the soil prior to planting or spray with serin

CYCLAMEN MITES

It is also called strawberry mites, cyclamen mites also belong to a group known as tarsonemid mites. They can attack a wide range of indoor plants beside cyclamens, as well as outdoor plants

The mites who usually congregate in buds & at the tips of shoots are too tiny to be seen with the naked eye.

They feed on plant tissue, causing distorted, puckered growth, often with light brown scabs. The plant development is generally stunted, shoots & flower buds may wither & die, and flowers that do open are discolored

In warm conditions of homes & greenhouses, the mites breed extremely rapidly & populations continue to increase, during the winter insecticides have relatively little effect on them, and infested plants are best destroyed as soon as the mites or their eggs are seen. This will help to prevent the spread of the mites to neighboring plants.

LEAF MINERS

These larvae eat their way between the two outer layers of the leaf , leaving a characteristic, winding silvery-beige trail.

Chrysanthemums & cinerarias are the most commonly affected houseplants.

Affected leaves are unsightly, but the plant seldom suffers greatly from an attack .Since these are both short-term, disposable plants, it is not generally necessary to take any action

Nonchemical control:

Remove & destroy all affected leaves

Suitable insecticides:

Neem oil or other horticultural oils such as sunspray oils

MEALYBUGS

These sap-sucking pests are rather like wood lice in appearance, but they have a white

, waxy, fluffy-looking coating that helps to protect them from insecticidal sprays.

They can move around the plant tend to remain immobile, and are often found clustered in the leaf axils. Cacti are particularly prone to attack by mealybugs

Root mealybugs present a greater problem, since they are not normally visible

Although they may be suspected where a plant fails to grow properly. White wooly masses can be found among the roots when a plant is turned out of its pot. Again, cacti & succulents are particularly at risk.

Nonchemical control:

These pests can be removed by lifting them off with a moist cotton swab. Or spray plants with a mixture of equal parts of rubbing alcohol & water. If the plant is infected with root mealybugs, wash the soil & pests from the roots & cut away damaged parts before the plants is repotting into fresh potting mix  

Suitable insecticides:

It is necessary to use systemic insecticides such as dimethoate to overcome the water-repellent effect of the pests, waxy coating.

RED SPIDER MITES

Almost invisible to the naked eye, red spider mites always form colonies, usually at the tips of shoots. Fine webbing may be seen on the under sides of leaves,

These sap-sucking pests cause fine yellowish speckling on the leaves, which take on the leaves, which take on a dried-up appearance and eventually fall

Red spiders mites over winter in wood work & in other nooks & crannies away from the plants, so infestations may be troublesome from year to year, particularly in green houses, a hot dry environment provides ideal conditions for them

Nonchemical control

Remove infested shoots & increase the humidity around plants by frequent misting with plain water

Suitable Insecticides

Kelthane

SCALE INSECTS 

Almost found attached to the undersides of leaves, usually along the midrib. Thick leathery leaves are most commonly attacked.

These are several different stages in the life cycle of the scale, but this immobile, unlifelike stage is the most noticeable. Honeydew, produced as they feed, often attracts sooty mold.

Nonchemical control

Scrape off scales with a fingernail or wipe them off firmly with a damp cloth.

Suitable insecticides

Horticultural oil, insecticidal soap, or the more toxic Malathion

SCIARID FLIES

It is also known as fungus gnats, they live in the soil, and when the plant is disturbed or watered , can be seen flying up a short  distance , sometimes in considerable numbers . The larvae feed on organic matter in the soil & may sometimes damage young roots.

Nonchemical control

Sciarid fly infestation is usually a sign of over watering & sodden soil . Let the surface of the soil dry out between watering

Suitable insecticides

Drench the soil with Malathion to rid the plant of the pest

THRIPS

These small, long bodied creatures with fringed wings, sometimes called thunder-flies, are abundant in homes & outdoors in spells of hot weather . they feed on plant tissue & cause a characteristic silvering & mottling of stems , foliage & flowers . they are usually present in large numbers & can often be seen hopping around the plants.

A large number of houseplants may be affected. Damage on plants is worst in hot, dry atmospheres

Nonchemical control

Make sure that plants are being given adequate water & increase humidity.

Suitable insecticides

Thrips can be controlled by spraying with most contact insecticides.

VINE WEEVILS

The larvae of the vine beetle, these relatively large , creamy white grubs live in the soil & eat plant roots. Often the total collapse of the plant is the first sign that anything is amiss. The 1-in/ 2.5-cm long gray –black adult beetles are active at night & can sometimes be seen crawling over the surface or biting notches out of leaf margins

Nonchemical control

Pick off & destroy adults whenever they are seen .destroy grubs found in the roots of plants to prevent the pests from spreading .biological control is available in the form of parasitic nematode , which can be used both as preventive & a treatment .

Suitable control

Drench the soil of plants at risk with gamma-HCH or mix a dust formulation of this chemical with soil when potting susceptible plants.

WHITE FLIES

A small, white, mothlike creatures can occur in large numbers ,rising up  from affected plants in a cloud when they are disturbed .they suck sap ,debilitating the plant, secreting honeydew, and attracting sooty mold .they are usually more of a problem in greenhouses than in the home.

Whiteflies have a complex life cycle in which only the adult stage is susceptible to insecticides. So spraying must be repeated regularly to catch each generation as it matures

Nonchemical control

Yellowish sticky cards can be hung near the plants to trap the adults as they fly

Suitable insecticides

Use enstar, insecticidal soap, & horticultural oils

Houseplant Diseases

BOTRYTIS

Usually known as gray mold , this fungus prevails in damp, cool conditions and is less common in home than in greenhouses .it starts on dead tissues & may spread to the rest of the plant .affected parts of the plants become covered in fluffy gray mold.

Nonchemical control

Remove dead & damaged parts of a plant promptly. Keep the atmosphere warmer & drier

Suitable insecticides

Most are effective

POWDERY MILDEW

This disease, in which powdery white patches form on foliage , is encouraged by hot, dry conditions

Nonchemical control

Adjust the humidity & temperature for plants

Suitable fungicides

Using Sulpher-based spray, to be sprayed at temperature below 80 F / 27 C.

RUST

A pale spots form on leaf surfaces, and brown concentric rings of spores appear on their undersides

Nonchemical control

Pick off and burn affected leaves. Destroy heavily affected plants\

Suitable fungicides

Using Sulpher-based spray, to be sprayed at temperature below 80 F / 27 C.

SOOTY MOLD

Although this fungal disorder is not a disease itself , it develop on the honeydew excreted by various sap-sucking pests such as scale insects, aphids & white flies , leaves become coated in a thick black deposit, which is unsightly & interferes with photosynthesis, checking plant growth .

Nonchemical control

Wipe the black deposit from foliage with a damp cloth

Suitable insecticides

Control any pests with an appropriate insecticide to get rid of the mold