The honeydew or nectar produced by the pests attracts and feeds the fungus. The black spots are a fungus … How to Treat Fungus on Cactus. The fungus does not harm or feed off the plants, but instead gets its nourishment from honeydew. Sooty black mold is a fungus that can appear on the surface of plant leaves, stems, twigs, branches and even fruits. Answer: It’s possible the white powder on your Kalanchoe luciae “Paddle Plant” (or Flapjack) is actually normal, but it could definitely be powdery mildew too. See, succulents store extra water in their leaves, roots and stems so they can survive the arid conditions of their native desert. Fungus gnats are a really big problem on tropical plants because they thrive in that moist soil that tropical plants love. Rot is sometimes a fungus "eating up" the dead plant tissue, but in that case something else triggered the start of tissue death. As you know, succulents are supposed to have a dry, gritty soil.It’s really not a conducive habitat for the fly larvae, so if you’re having problems, … It is often quite impossible to diagnose which fungal organism is causing the spots, but often that is unimportant since treatments are generally the same. Once there is a fungus affecting your cactus, it can be difficult to stop. In a true fungal attack, there is a fungus growing inside the plant tissue that kills it as it goes. Black or sooty mold is a fungal infection often seen on plants that are also infected with pests such as whitefly or mealybugs. A few fungi types damage the roots and eventually, the whole plant, so once their visual damage is seen, it is too late for the plant. The most pressing of concerns with succulents is when you notice the stems are rotted. It’s drowning. The fix for black stem rot is to repot the plant. That can be fixed, so you don’t need to toss the plant and start again. If the leaves are turning black, that means the succulent is rotting from the root up due to too much water. Too much water overfills the plant’s water storage tissue and causes it to bloat and explode. Black or Sooty Mold. How to Revive a Succulent with Black Stem Rot. If the plant is rife with lesions, it may be best to find some uninfected healthy material and start a new plant with a cutting. All you need is your trusted pruners to cut away the rotted part of the stem. Honeydew is a sticky, sweet substance that certain insects secrete. The paddle plant naturally produces a powdery white coating that helps keep it healthy. This is what makes it turn brown and dry. It can also be a sign that the plant is sitting in the wrong potting mix. Treatment: Fungal … If damage isn’t severe, a fungicide spray can usually help. You can see it in the picture here. Fungus spots on cactus pads are common. Black leaves on succulents are often a sign of overwatering. Usually the leaves will also feel soft and mushy.