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.
When a Desert Rose flower holds water, it may begin to rot. The rot spreads part way down the stem before the plant heals itself. Caudex Rot affects the swollen base and main stem of Desert Roses. All the leaves on infected plants suddenly turn yellow and droop, but do not fall off. An infected plant usually dies, but some larger Desert Roses may heal themselves.