Diseases of the African violetare a frequent cause of failure in the cultivation of this plant. Some symptoms, such ashanging and curling leaves of African violet , may be the result of easy-to-eliminate care errors. On the other hand,spots on the leaves of violetmay already indicate an attack of a fungal disease that requires immediate control. Here are the most dangerousdiseases and pests of the African violetand effective methods of combating them.
African violet diseases
Stains on the leaves of the African violet
Whenhas watery brown spots on the lower leaves of an African violetand the flower petals become watery, then turn brown and fall off, it may be gray mold. The culprit of this disease of the African violet is the fungus Botrytis cinerea. Gray mold grows where there is high humidity, low air exchange and poor lighting. A gray, dusty coating appears on the surface of the stains. The fungus Botrytis cinerea attacks especially over-fertilized plants. It is especially dangerous in winter and on cloudy days.
In the fight against this disease of the African violetthe most important thing is prevention, i.e. avoiding soaking the leaves and flowers of the violet during watering. In the winter, you should stop fertilizing the violets. When we notice the firstsymptoms of gray mold on the African violet , remove and destroy all the infected parts of the plant, and then spray the violet 2 times (with a lapse of 10 days) with fungicidal preparations such as: Teldor 500 SC ( 0.25 ml / 250 ml of water), Kaptan suspension 50 WP (0.5 g / 250 ml of water), Miedzian 50 WP (0.6 g / 250 ml of water) or Biosept Active (0.1 ml / 200 ml of water ).After spraying, place the pot with the violet in an airy place so that the plant is thoroughly dry.
Ifviolet leaves are covered with irregular, black-brown, slightly watery spots , drying out from the inside, and there is a lighter border around these spots, it is corinosporosis -African violetfungal disease, caused by Drechslera cassiicola. When we notice symptoms of corinosporosis, we remove and destroy all the diseased violet leaves. Then spray the plant (1-2 times) with fungicides: Topsin M 500 SC (0.25 ml / 250 ml of water), Rovral Aquaflo 500 SC (0.05 ml / 250 ml of water), alternating with biopreparations, e.g. Biosept Active (0.1 ml / 200 ml of water), Bioczos (5 ml / 250 ml of water).
Irregular, light yellow spots appear on the surface of the violet leaves(streaks, circles), initially watery, and then dead tissue (so-called parchment stains) remain in their place. This is the result of soaking the violet leaves with water (e.g. during watering).It is recommended not to water the violets from the top, but to use the soaking method to avoid soaking the leaves. It consists in putting the pot with the violet into a vessel filled with water. We leave the plant in the dish for about 15-30 minutes. During this time, the plant will take up the amount of water it needs. Then put the pot in a place where it can easily drain the excess water.
Forwatering the African violetyou should use water with a temperature higher by 1-2 ° C than the temperature in the room . African violets growing in the sun should be placed in the shade an hour before watering. Permanent place, they can be put aside only when any water drops disappear from the surface of the leaves.
African violet leaves hang and curl
Violet wilt, combined with rot of the stem base, petioles and flower stalks , causes the fungus Phytophtora nicotianae, which causes a disease called phytophthorosis.Phytophthora develops at a temperature of 20-25 ° C and high air and substrate humidity. Especially often it attacks plants grown in soil with a high content of peat.
TaAfrican violet disease is very difficult to fightInfested violets should be removed together with the soil and the pot, while the remaining ones growing in the vicinity should be watered with the fungicide Aliette 80 WG (0.5 g / 250 ml water), Amistar 250 SC (0.03 ml / 250 ml water) or Folpan 80 WG (0.5 g / 250 ml water). We can also use Biosept Active or Bioczos in a dose of 50 ml of liquid per pot with a diameter of 10 cm.
When violet leaves hang from the pot, they become soft and curlit may be a symptom of root rot due to over-irrigation. To avoid this, we water the violets twice a week using the siphon method. We replant the violets with symptoms of the disease to fresh soil and a new pot. Before that, we remove the rotten parts of the roots and the most wilted leaves.
Whenleaves of the African violet curl downwards , and there are no signs of pest feeding on their surface, it means that they have been exposed to low temperatures. In the winter months, place pots with violets on the windowsill before opening the windows. Remove leaves damaged by a cold blast of air and transfer the violet to a warm place (15-20 ° C). In a room where violets hibernate, the temperature should not be lower than 12 ° C.
African violet leaves pests
Very commonpests attacking African violetsare thrips, mainly Western thrips. In the event of an attack of this pest , silvery spots appear on the leaves and petals of the violet , visible on them corkiness (rough warts) and scattered pollen. Female western thrips are approximately 1.7 mm long, yellow-orange or orange-brown. The males are smaller, grow up to 1.3 mm in length and are yellow.Thrips feed on plant sap, puncturing the leaf tissue. They also often nibble at the anthers of flowers. On the lower side of the leaf and around the pot there are thrips droppings in the form of small black lumps.
Thrips can get into the apartment without wind (e.g. through an open window), brought on cut flowers and purchased violets, from uncertain sources. Adult thrips are captured on blue pest sticky boards placed between pots of violets. The development of thrips is stopped by high air humidity, so you should place the pot with the violet on the bases filled with water and a layer of pebbles. Place the Provado Combi Pin 02 PR insecticide sticks in the ground or the Green House insecticide sticks. We can also use natural preparations available for sale, such as Emulpar Spray or Multi Insekt Substral Naturen. These products are sold in a convenient package with a sprayer, in a ready-to-use form.When these preparations do not work, we use chemical agents for spraying: Mospilan 20 SP (0.1 g / 250 ml of water), ABC on aphids AL (available in the form of a ready-to-use liquid), Apacz 50 WG (0.1 g / 250 ml of water) or Vertimec 018 EC (0.13 ml / 250 ml of water).
The cyclamen mite is very sensitive to sunlight and requires high air humidity. It can be combated by exposing the violet to direct sunlight for several hours. However, the light should not be too intense. We can fight cyclamen mites by using natural or chemical sprays. Natural preparations for combating cyclamen mites are Afik AE (the preparation is sold in the form of a ready-to-use liquid) or Promanal 60 EC (5 ml / 250 ml of water). When other methods fail, spray Sanmite 20 WP (0.25 g / 250 ml water) or Vertimec 018 EC (0.13 ml / 250 ml water).
MSc Eng. Agnieszka Lach
