Improperly cared for cacti can become ill. When acactus withers, wilt, rotor discoloration, it is a sign that it is a physiological, bacterial or fungal disease. The condition for effectivecombating cactus diseasesis their early diagnosis and proper treatment. Learn about the most commoncactus diseasesand learn how to help weakened plants.
Diseases of cacti. Why does a cactus wither, wrinkle and rot?
Fig. depositphotos.com
Physiological diseases of cacti
1. Dehydration
During the growing season, cacti need a lot of water for proper development. Too rare or too little watering of cacti stops their growth and causes them to go dormant. If conditions do not improve for a long time, the plants begin to use up the water stored in the stems. As a result,cacti start to wrinkle and wiltAbundant watering of the cacti at this point may not help, because the substrate in the pot becomes parched after prolonged drying and stops absorbing water. Then the plants need to be transplanted to fresh substrate.
To avoid dehydration of cactiwe must try to water them during the growing season at least once every 3 weeks. This must be done in such a way that the water penetrates deep into the ground, all the way to the bottom of the pot. It is best to put pots with cacti in a bowl of water and let the entire substrate in the pots be soaked with moisture.
2. Burns
The rapid increase in temperature, strong sunlight and the lack of proper ventilation lead to thermal infestation of plants. This causesthe skin of the cactusto turn red and burns over time. Burns appear asrecessed white patches on cactithat can remain on plants for several years.
Cacti burns most often in spring, when they are moved from the rooms where they wintered to the window sill, and in summer, after longer periods of cloudy weather.To protect the cacti from burns, , shade them with white paper in the afternoon hours and ensure proper ventilation of the rooms in which they are grown.
3. Chlorosis, fading
Too little sunlight causesyellowing of the cactus shootsThese symptoms are called fading, often accompanied bydeformation of the shoots caused by the stretching of the plants towards the sun Moving the cacti to a better sunlit place allows them to recover.
Distortion of cactus shoot caused by insufficient sun
Fig. © Agnieszka Lach
On the other hand,cactus chlorosis is caused by a deficiency of magnesium, iron or manganeseIt occurs as a result of the impossibility of taking these components due to the excessively high pH of the substrate. Too high pH of the substrate (above 7) also causeswilting and rotting of cactiTo maintain the correct pH of the substrate,cacti must be watered with soft or acidified waterplants with symptoms nutrient deficiencies should be fed with multi-component fertilizer diluted in water or transplanted into a fresh substrate.
Bacterial diseases of cacti
1. Cactus Soft Rot
It is a bacterial disease of cacti that occurs most often in the spring.It is caused by the bacterium Erwinia carotovora. It is caused by watering cacti during low temperatures and the lack of airing of plants. The firstsymptoms of soft rot are visible at the base of the cactus shoot as gray, slightly sunken spotsThe spots on the shoots grow rapidly and turn brown over time, andthe cactus begins to rot The cactus stalk breaks down at the spot, and a yellowish, foul-smelling goo comes out of the stain.
In the early stages of the disease, the rescue for cactiis to thoroughly clean the infected areas into he althy tissue and coat them with charcoal and spray the plants with Miedzian 50 WP or Biosept Active. Heavily infested plants cannot be saved anymore, so they should be thrown away together with the substrate.
Cactus fungal diseases
1. Shoot blotch
Blotch on cactus shoots is a fungal diseasecaused by the fungus Dreschlera cactivora.As a result of this disease , light, dry and slightly recessed spots appear on the cactus shoots, several centimeters in diameter.Additionally, the tops of the shoots and damaged cactus tissues turn yellow. The spots spread very quickly and diseased shoot parts or entire plants die.
To avoid the appearance of this disease,avoid growing cacti in conditions of too high air humidity and substratePlants should be positioned so that they do not damage each other with thorns, because infection often occurs at the site of wounds. When the first symptoms of shoot blotch appear, spray the cacti with a fungicide, eg Topsin M 500 SC. We never use it indoors (when spraying, take the cacti outside).
2. Phytophthorosis
Phytophthora, caused by the fungus Phytophthora cactorum, manifests asbrown spots initially appearing at the base of the cactus shoots The spots grow rapidly and diseased shoot parts or entire plants die.Too frequent and abundant watering of cacti is favored by the development of phytophthoraDiseased plants should be discarded, and others should be watered with the biological agent Polyversum WP (0.5 g per 1 l of water).
MSc Eng. Agnieszka Lach
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