Most likely, you will never have to worry about insect pests or diseases attacking your African violets.
Culturally healthy, well-grown houseplants can resist most plant enemies and will continue to live year after year with little danger of being infested.
Control Pests and Diseases
Insect pests and diseases that attack African violets come from several sources. The old proverb, “It is better to be safe than sorry,” is most applicable if you wish to avoid difficulty.
Follow these simple rules, and the various ailments discussed here will be no problem:
1. After handling or watering new plants, wash both your hands and watering can before working with your other plants. You may thoughtlessly spread an infection yourself from pot to pot.
2. Remove any plant from the rest of your collection that has changed in appearance or is beginning to look “different.” Put it in another room and watch it carefully.
3. Don’t place a newly purchased or gift plant with your other saintpaulias. Beware of strangers! Keep it in a separate window for six weeks or two months and wait. If it is free of disease, then add it to your collection.
4. Purchase from reliable sources. Many commercial florists follow regular health programs to keep their stock in clean condition. They no more want you to have an ailing African violet than have one themselves.
Cyclamen Mite
The cyclamen mite is one of the most destructive pests that attack African violets. It is so small that it cannot be seen without the aid of a hand lens, which makes it all the more subtle and dangerous.
Its presence may be first suspected when the blossoms become discolored and abnormal and the young central leaves of the crown of the plant become deformed, brittle and take on a characteristic hairy or wooly condition with a gray-yellowish overcast. The crown will eventually die out if the plant isn’t treated.
Treatments For Cyclamen Mites
There are several effective treatments for satisfactorily combating cyclamen mites. Some better known are NNOR, Optox, Endopest, sodium selenate, and DDT. NNOR may be used at the rate of I teaspoonful per gallon of lukewarm water.
Stir well when mixing. This solution can be used as either a spray or dip. To dip a plant, have a large container so the entire plant may be submerged. Allow the NNOR to soak through the soil.
If spraying, be sure to get the crown and the leaves’ upper and lower surfaces thoroughly wet. Set treated plants aside in a shady location for several hours before exposing them to direct light. Repeat the treatment in seven days three times, then once a month.
Optox is a dependable spray that may be used in 1 ounce to three gallons of lukewarm water. This, too, may be used as a spray or a dip and should be repeated each week for three applications, then once a month.
Endopest is dry dust and comes in a handy applicator, making it easy to use. Plants should be treated every four days, applying the dust very lightly and evenly over the crown of the plant and on the upper and lower surfaces of the leaves.
Dusting should be continued for 30 days at least. When the plant has recovered, the residue of the Endopest may be cleaned off with a warm water shower.
Although widely used commercially, sodium selenate is a dangerous poison and is not recommended for home use. It is applied through the soil and is both lasting and effective.
A mild infestation of cyclamen mites may be cleaned up in a few weeks. However, it will probably take about two months for you to see any improvement in the foliage.
When the new crown grows, the gnarled, twisted leaves may be pinched out, and the new center will soon cover the mite damage.
Controlling Root-Knot Nematode
Saintpaulia growers in many sections of the country are becoming painfully aware that another serious threat to successful African violet culture is the root-knot nematode.
These are fine, threadlike parasitic worms that attack the roots and plant stalks, causing the plant to wilt and eventually die.
The foliage loses its glossy, dark green color, becoming pale and dull, and the outer leaves droop. Small pulpy nodules or enlargements will be found on the roots, and the stalk will be knotty and spongy.
There is no known easy-to-use home cure for plants infested with nematodes. Thus, it is evident that the first thing to do when a plant is infested is discarding it.
Don’t throw it on the compost pile because the nematodes may survive and find a new host.
Destroy the plant and soil, and carefully disinfect the pot before using it again. It is said that nematodes can pass from one pot to another if they are grouped close together on wet sand or gravel. They can also swim in tepid or cold water from pot to pot if kept in a common container.
Re-rooting Plants
Rerooting plants infested with root-knot nematodes has proven to be a waste of time. The plant may be cut back to what appears to be a healthy stalk and rerooted, but in several weeks the nematodes will reappear.
Since the presence of root-knot nematodes cannot be detected in the soil before it is used, it is best to plant only in sterilized soil. This includes all types of animal fertilizers commonly added to potting soil which may have had an opportunity of becoming infested.
It is also safer to sterilize all rooting mediums if there is arty suspicion that they may have become contaminated. Throw away all infected plants and use only nematode-free stock for propagation.
Control Mealy Bugs
The mealybug looks like a very small speck of white cotton. It gives an African violet a webby, dusty gray appearance on the flower stem and foliage.
Mealybugs are sucking insects that slowly drain the plant of its vitality. Control measures are not difficult, but a single-crown plant is more easily cleaned up than a multiple-crown plant.
Clean off the mealy bugs for a light infestation and gently rub the spot with a swab dipped in rubbing alcohol. Inspect the plants for newly hatched offenders every few days and clean them up promptly.
Should you have difficulty because of the dense, brittle foliage, plants may be dipped as for cyclamen mites, and the condition will soon be under control.
Springtails
Springtails cause more harm to the owner’s pride than they do to Saint Paulias. These tiny, fast-moving insects live in the soil and may be seen moving around in watering trays and on the bottom of pots.
There is no need for an alarm. They can be eradicated by watering with a mild solution of Optox or NNOR. Clorox, too, may be used at the rate of 1 teaspoonful to a pint of warm water.
Black flies that live and breed in the soil are also annoying. They are troublesome from a nuisance standpoint but cause no actual harm. They are easily eliminated with DDT or any other previously mentioned insecticides.
Crown Rot
Saintpaulias that suddenly flop, with drooping lower leaves dangling around the top of the pot, may be assumed to have crown rot. The plant seems to need water, but no amount of moisture will crisp the foliage.
This condition may be brought about by overwatering, especially in the fall and spring, by planting the crown too deeply in the soil, or by irregular care.
By irregular care, we mean allowing the plant to become excessively hot or dry and then generously watering it until it is soggy—”desert to swamp conditions.”
African violets with crown rot may be rerooted. Remove the plant from the pot, carefully shaking the soil away from the roots. Cut off the dead, dried-out roots and stem.
Trim back to the live green portion of the stalk and reroot in either peat and vermiculite, sand, soil, water, or any other rooting medium as you would a leaf cutting.
Despite all the possible insect pests and diseases mentioned, African violets are America’s favorite and most successful house plant. No other potted plant provides its owner with so many beautiful blossoms for so many months.
44659 by Alma Wright