Ask AI: Explain the following plant disease symptoms a) Knot b) Rusts

a) Knots are growths on plant stems or roots caused by a variety of plant pathogens, including bacteria, fungi, and viruses. Knots can vary in size and shape, and may be raised or sunken. They can interfere with the movement of water and nutrients and damage the structure of the plant. Some common plant diseases that produce knots include crown gall and root-knot nematode. b) Rusts are a group of fungal diseases that affect many different plants, including trees, shrubs, and crops. Rust infections appear as small, discolored spots on leaves, stems, or flowers, which eventually grow and spread to form masses of reddish-brown or orange powdery spores. Rusts can weaken plant growth and make them more susceptible to other diseases or pest damage. Common rust diseases include cedar-apple rust, wheat rust, and rose rust.