they might get their long hair from their father's genes. They might also have long hair phenomenally.
Although the mother may look shorthaired, she may be carrying a hidden, or recessive, longhaired mutation. So if she mates with a longhaired tom, half the kittens will be longhaired. Or if she mates with a shorthaired tom carrying the same hidden longhaired gene, one in four kittens will be longhaired.
Most likely, it would effect many trees depending on the rate of infection and how much of this microorganism is released to the environment. I hope that helped :)