To be a successful gardener, you need to sharpen your “plant doctor” skills. Plants, like people, exhibit symptoms when they are under attack or sick. It’s important to pay attention to your plants and recognize when things start to change.
Plant problems fall into just a few main categories: stress, insect infestations, and disease. These are all interrelated and a plant under stress is an easy target for the others.
Stress in your garden.
Stress occurs when their positive environment is altered. Plants become stressed by drought and lack of water. They are also susceptible to over watering, which can bring on mold, fungus, or attract slugs. Quick changes in weather, and specifically cold and frost, can damage plants and cause stress. The number one stress factor by far is most likely you. Extreme fertilization, pruning, and damage to roots or large limbs may result in plant decline and in severe cases the death of the plant.
Fungus and Disease.
Fungus typically shows up as brown spots or tipping on leaves and foliage. It’s the general discoloring of leaves. Unfortunately, by the time you see damage on the leaves, the stems and roots may be suffering damage and the plant is in serious decline.
Plants that are afflicted with fungus or a bacterial infection need to be treated. The leaves and buds will not recover from a fungus or disease infestation. They will need to be pruned back and removed to stop spread and to allow new growth to emerge.
Black spot is a common fugus. This is a “leaf spot” disease and occurs when the air is wet and warm. The dampness allows airborne spores to cling to the leaves of plants and take hold. Warm, damp air helps spread fungus, so plants that naturally thrive in that environment like orchids and succulents need to be observed for signs of infection.
Pests
The first sign of predator attack might be egg sacks, leaf browning, or ragged leaf edges where bugs are feasting. Many insects can eat strip foliage from a plant overnight.
Insects will usually first infect the bloom on a plant where the soft foliage is vulnerable, before moving to leaves and stems.