Question

Why are papaya stems greenish black and what's the cause of their strength?

Answer 1

Answer:

Explanation:

Disease symptoms

It is characterized by the appearance of water-soaked patches on the stem near the ground level.

These patches enlarge rapidly and girdle the stem, causing rotting of the tissues, which then turn dark brown or black. Such affected plants withstand strong wind and topple over and die.

If the disease attack is mild, only one side of the stem rots and the plants remain stunted.

Fruit if formed are shriveled and malformed. Gradually the plant dies.

Survival and spread

Resting spore, Oospore, germinates and release zoospores which along with irrigation water spread throughout the field.

Favourable condition

High relative humidity and rainy condition favors the severe disease development in sick soil.