What is Apple rubbery wood?

Apple rubbery wood virus, also known as apple rubodvirus is a viral disease that causes apple rubbery wood in apple and pear cultivars. There are two varieties: ARWV 1 and ARWV 2. It gets its name from its distinctive effect that it has on its host trees, which show unusual flexibility in the stems and branches after a few years of infection. This often results in the maturing fruits of the tree to weigh down the branches such that they lay on the ground. Apple rubbery wood, or ARW, occurs worldwide, affecting apple and pear cultivars in most developed countries.