Human plant infection is very rare, but it does occur. The main pathogen of concern is a bacterium known as Pseudomonas aeruginosa, which causes a type of mild rot in plants. Aeruginosa infections in humans can invade almost any tissue in the human body, provided they are already weakened. In most cases, the answer is no.
The fungi, bacteria, viruses and nematodes that cause diseases in plants are very different from those that cause disease in humans and other animals. However, some plant pathogens can infect both humans and plants, and those that do tend to be opportunistic pathogens, especially in a segment of the population at risk. For example, people with weakened or compromised immune systems, who take certain medications, or who have medical conditions or other causes that may cause the human immune system to weaken (immunosuppressed). From rabies to avian flu and HIV, diseases that pass from animals to humans are a well-known phenomenon.
But a virus that jumps from plants to humans? Never. At least, that's what doctors thought until Didier Raoult, from the University of the Mediterranean in Marseille (France), discovered that the mild speckled virus found in peppers may be causing fever, aches and itching in humans. If validated, it would be the first time that a plant virus has been discovered to cause problems in people. Do you see those yellow and red spots on the leaves on the left? Those wheat plants are sick.
They have a disease called wheat leaf rust. Wheat leaf rust is caused by a fungus and, like many fungi, spreads from one place to another in tiny particles called spores. When wheat rust spores land on the leaves of a healthy wheat plant, that plant can become infected. According to the Cereal Diseases Laboratory, wheat rust absorbs nutrients from plant tissues and makes the plant more susceptible to infection by other fungi and bacteria.
Unless the disease is simply a superficial stain (such as a stain of soot and a speck on an apple), it may be best to avoid sick products. You're not likely to get an illness when working with sick plants in your garden, but it's a potential risk (depending on the infection) and should be considered. Plant diseases represent a major problem for farmers around the world. In some crops, diseases can reduce yields by more than 70 percent, and failure to address the problem can result in financial ruin or famine.
