This is because there occur in addition to weakened stems also much healthier, even completely undamaged, but can not resist to a few kilograms of heavy wet mass of weakened stems, falling to the ground due to the Domino Effect (explained elsewhere), what causes the break.
Hii ni kwa sababu kuna kutokea ndani yake addition dhaifu inatokana pia sana na afya njema, hata kabisa undamaged, lakini hawezi kupinga kwa kilo chache ya molekuli nzito mvua ya mashina dhaifu, kuanguka chini kutokana na Athari Domino (Explained Kwingineko), nini Inayotoza mapumziko.