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.
You have a rose thatâs susceptible to black spot, a fungus disease. Yellow leaves and spots on a roses can be a disheartening sight. It can ruin the overall effect of the rose bush when the leaves turn yellow. To protect your plants, you have have to spray a fungicide.