Yield, Quality Traits and Black Root Rot during Storage and Distribution of Carrots Grown in a Chalara Infested Field

Carrot is one of the major vegetable crops produced and consumed in Switzerland. In the past years poor shelf life of carrots has led to frequent complaints from consumers and retailers. The most critical deficiency was the development of black root rot spot on carrots caused by Chalara species. Previous investigations showed that all the tested fields in the main carrot production regions of Switzerland were contaminated with Chalara sp. In Switzerland, carrots for long term storage are harvested in October and early November. They then are stored in wooden bins in refrigerated rooms for a period of up to seven months. It is recommended to use perforated plastic bin liners to minimize water losses of carrots. The effect of Chalara field contamination, cooling techniques, storage with or without polyethylene liners on overall yield of market-able carrots, quality traits and the occurrence of black root rot were investigated. Storage of carrots at temperatures between 0-4 degrees C prevented the development of Chalara. Excessive water losses resulted in wilting of carrots, and maintenance of high air humidity was critical during the entire storage. Hence, lining bins with perforated plastic foil is advisable in most storage rooms. In addition, replacing recycled water with fresh tap water during carrot washing and the maintenance of a closed cool chain below 8 degrees C after washing, packaging and in retail prevented the occurrence of black root rot and other decay. In conclusion, proper postharvest processing, in particular optimal washing operations, can assure acceptable shelf life and high quality of carrots grown in Chalara infested fields.