What are the common pests and diseases of Agave americana 'Marginata'?
I. Introduction
It is a perennial, and its leaves can stay green all year round. It is generally planted in gardens, and is grown in places such as the Southwest and South China. It originated in the Americas, can be used as an ornamental plant, and can also be used to treat the body; it can treat cough and asthma, problems with the meridians, and so on. Its taste is rather sweet with a bit of pungency, and its leaves contain a substance called saponin.
II. Diseases
1. The diseases it commonly gets include leaf spot, in which brown spots grow on the leaves; anthracnose mainly erodes the leaves, causing them to develop lesions and show diseased spots, with the color gradually darkening and the area gradually expanding, until finally the entire leaf is eroded and rots away. There is another disease it often gets, and that is gray mold.
2. Prevention and control: It suffers from disease erosion mainly because the environment is too poor and the owner has not been attentive. If the air is too stuffy and hot, and at the same time very humid, with poor ventilation, or if too much nitrogen fertilizer is used, it will be prone to disease, so preventive work should be done well in normal times.
When it is very hot in summer, give it ventilation, and fertilize reasonably to ensure its growth has enough elements, especially enough trace elements. If it has already become diseased, remove the diseased leaves to avoid infecting everything around, then use a little Bordeaux mixture and the like, according to the dosage on the instructions, spraying it once a week. The best method is to use several kinds of medicine alternately, which can avoid the emergence of drug resistance.
III. Pests
Its most common pests are scale insects, as well as mealybugs and so on. If you find insects on its leaves, you can remove them manually by picking them off with tweezers, and then spray some medicine on the leaves. If insects are found in the soil, you need to promptly change its pot and soil, and also disinfect its whole body and prune the rotting roots. Finally, repot it, and before that do a good job of disinfection; the soil must not contain insect eggs, and fresh soil must be used. If medicine is needed, dichlorvos can be used, and in daily care attention should be paid to giving it ventilation.