According to the University of Minnesota, bamboo grown in the northern parts of the United States have few problems with leaf spots and other bamboo diseases. However, bamboo grown in the southern United States can have problems with common local plant diseases. Understanding the source and effects of these brown spots can help you treat the problem more effectively.
Geographical Differences in Causes
According to the University of Idaho, bamboo in the United States has few diseases and problems; however, wilts and leaf spots are a problem in Asia that have not yet spread to North America and Europe. Insects that can cause brown spots on bamboo leaves are also not common in the United States. Problems with bamboo in the United States based on existing plant pests and pathogens are treated in the same way as when domestic plants are found infested with a particular problem.
Brown spots on bamboo in the United States could be caused by a variety of problems. Aphids can sometimes result in spots on bamboo. Another insect that can sometimes affect bamboo are various native borers. Different fungal problems, bacterial infestations, smut and rust can sometimes affect bamboo in the southern United States. Identifying the exact problem can be difficult, however. If you see spots, consult your local county agricultural extension for a definitive diagnosis.
Preventing insect infestations and disease problems with bamboo is primarily a function of keeping your bamboo healthy. According to Systematic and Applied Acarology, the best way to prevent problems with a bamboo grove is to either increase its strength and health, or implement practices that ensure that the planting is consistently healthy. Strong bamboo growth is naturally more resistant to pests and disease than less healthy groves.
Treatment for problems can range from fertilization to help increase the health of the grove to adding natural predators to insect problems like aphids, according to Systematic and Applied Acarology. Rusts, virus, fungus or bacterial infections can also be treated by increasing grove health, but may require other interventions like application of anti-fungal sprays.
In most cases, damage to individual canes isn't severe. A study of bamboo groves in Fujian, China, by Yanxuan Zhang showed heavy damage on only five percent of the canes. Moderate damage affected 30 percent of the canes, while 40 percent were lightly damaged in infested groves. No damage was found on 25 percent of the canes. How each problem affected the bamboo was different, but in many cases affected plants had lower chlorophyll levels and efficiency.