MSU Extension Chestnuts

Internal kernel breakdown (IKB) is caused when Chinese cultivars pollenize European hybrids like Colossal. To avoid IKB, growers should not interplant Chinese and European varieties and should separate orchards by a minimum of 1,000 feet, preferably placing Chinese chestnut down wind from European hybrids to limit pollen exchange.

Internal kernel breakdown causing browning in Colossal. 

Creamy, white appearance of healthy chestnut kernel.