The atmospheric chemistry would be upset by cutting out sunlight. It would be like a nuclear winter and could last for tens of thousands of years. These comets are 200-300km (186 miles) in diameter they are sheer monsters and could sterilise the earth if we are hit by one.
Heat stress â Another reason for rose leaves turning yellow is the rose bush is under some sort of stress. A common cause of stress is heat stress. The rose bush turns yellow and drops its foliage in an effort to cool down in the case of heat stress.
What causes tomato plant leaves to turn yellow? Yellow leaves that have purple, distorted veins are a sign that psyllids have infested the tomato plant. Treatment involves looking on the bottom of leaves for insects, removing them and applying a pesticide to the growing area. Tomato plants that stop growing and turn yellow all over may have the curly top virus. The beet leafhopper transmits this disease by jumping from plant to plant.