U.S. scientists have discovered a link between the plant pathogen phytophthora and skin separation in bell peppers, but say much work remains before the disease can be controlled altogether.

Dr. Andy Wyenandt

Speaking at last week's 22nd International Pepper Conference in Chile's Viña del Mar, a researcher from New Jersey-based Rutgers University discussed what he and his team had discovered from more than 10 years of studies.

Phytophthora is one of the most serious diseases affecting the state's 4000 acres of bell pepper production, and more than 75% of the vegetables are made up of cultivars with some level or resistance or tolerance.

The disease causes rot and can often results in large economic losses for growers.

While skin separation - or 'silvering' - does not affect the fruit quality or reduce the product's shelf life, it does leave a grey discoloration on the skin's surface and renders the fruit almost entirely unmarketable.

"Bell peppers need to be dark green, glossy, with four lobes, thick walls, and shallow shoulders. If that type of cultivar is not met they will not be growing in the state of New Jersey," said vegetable pathology expert Dr. Andy Wyenandt.

Five bell pepper varieties were tested in Wyenandt's study - Alliance, Revolution, Camelot, Aristotle and Paladin, with the latter two traditionally displaying the highest resistant to phytophthora.

"In general, regardless of production system, we saw more silvering in the Aristotle and Paladin than we saw in Alliance and Camelot during the study of phythothphora-suspectible varieties," he said.

He added although the production method did not play a huge role, more silvering was detected in bell peppers grown in double or single mulch - used in around 90% of New Jersey's production - than those grown in the bare soil.

Another research team from the University of Florida has also been conducting studies to evaluate bell pepper varieties for disease resistance on the state's sandy soils.

Phytophthora is a serious issue in Florida as well as New Jersey, with the favorable weather meaning significant losses are incurred by the US$205 million bell pepper industry.

Assistant professor Dr. Monica Ozores-Hampton tested the resistance of nine cultivars in a commercial field that had a history of the disease.

While both studies took place in the same country, it was noted that different varieties may display varying levels of resistance to phytophthora under different growing conditions.

Ozores found that while the disease was far more common in Brigadier, Aristotle and Hunter than the other six - including Archimedes, Intruder, Paladin and Vanguard - there were a significant amount of variance throughout the field amongst the same cultivar.

The weather was also relatively dry during the study, and the results may not be conclusive as phytophthora needed cold and wet conditions to thrive.

Ozores added a 'tremendous' amount of work was still left to be done on the topic.

Photo: www.shutterstock.com

www.freshfruitportal.com