Q: Why do my plants get sick?
A: There are several reasons. Firstly, the plants you bought may have been infected by disease agents such as fungi, bacteria, viruses or nematodes. So the disease comes from the original source from which you got the plants. Secondly, the disease comes from adjacent plants in your yard or area by means of transmission, such as insects, wind, rain, and/or  mechanical contacts, etc.. Thirdly, the soil in which the plant is growing contains nematodes or pathogenic fungi. Finally, your plants may have been suffering nutritional or environmental stresses for a significant period and then overcome by certain weak pathogens.

Q: What should I pay attention to when I buy a plant from nurseries?
A. When you choose a plant from a nursery, examine the plant very carefully for any diseases, especially for viral diseases and nematodes. Most nurseries sell healthy plants but there is no guarantee that all plants in the store are 100% free of diseases. Some plants or nursery stocks are infected by viruses but do not show symptoms, and seller or buyer usually assume that those plants are healthy. Also, Nematodes that usually attack the root system of plants are overlooked by many buyers. To ensure the plant you buy is healthy, look for those nursery stocks or plants that are certified to be free of or resistant to certain diseases. You also can check the individual plant to see if there is any disease symptom shown. The most common symptoms you should focus on are mosaic, leaf roll, canker, mold, mildew, gall, knot, overgrowth, poor growth, and yellowing, etc. For more information on the symptoms of plants, click "The most common symptoms on plants".

Q: Is plant disease curable?
A: Generally, it is much better and more effective to prevent diseases rather than to cure a disease problem. Certain fungal diseases can be effectively treated by fungicides. However it is usually difficult to treat plant diseases caused by viruses or nematodes.

Q. What should I do if a plant gets sick?
A: Firstly, get help from a local horticulturist for diagnosis. If it is a water or soil problem, he or she may give you suggestion such as how much water and what nutrients you should apply to the plant each week. If it is a problem caused by infectious agents such as fungi, viruses, or nematodes, you may seek help from a plant pathologist. He/she will determine what is really causing the problem and provide you with information on how to control the problem.

Q. The tree grows so poorly, but I did not see any bugs.
A: There are many factors that contribute to the poor growth of a tree. Even though you did not see any bugs, that does not mean there is no bugs on your tree. Some bugs are too tiny to be seen by naked eyes or they live inside the tree, i.e. trunk or leaves. Even there is no bug present in your tree, there are still many microorganisms such as fungi, bacteria, viruses, nematodes that can cause poor growth of the tree. Those microorganisms are called as "plant pathogens". Sometimes, unsuitable soil type or unfavorable environment also can cause the problem.

Q. I have two big trees in my back yard, they have something wrong and are dying. I don't want to lose the trees.
A. It is a difficult situation for both the client and the plant pathologist. When a tree is found dying, it is probably too late to rescue it. However, plant pathologist will still investigate the problem and found out the real killer. If the tree is totally dead, it is very difficult to find out the real killer because many saprophytic organisms have dominated the dead tree.