January 7, 2010 – Pepeekeo, Hawaii

Pepeekeo farmer Richard Ha, whose Hamakua Springs Country Farm grows tomatoes known all over the state, recently alerted Hawaii to a new threat to the island tomato industry via his blog.

According to Ha, the University of Hawaii’s College of Tropical Agriculture and Human Resources said they found the “tomato yellow leaf curl” in Maui tomato samples.

“As far as I know, this is the most devastating tomato virus worldwide!” warned plant pathologist Dr. John Hu in a November note. “It has been reported in many other countries including the mainland USA. However, this is the first time we have seen it in Hawaii. Potentially, it could be a very significant problem for you and the entire tomato industry in Hawaii. Plus, we may have similar viruses in other vegetable crops in Hawaii.”

According to info CTAHR provided Ha:

Tomato yellow leaf curl is a destructive viral disease of tomato caused by Tomato yellow leaf curl virus (TYLCV). In tropical and subtropical regions, total losses of tomato crops have been reported. TYLCV is widespread and can be found in most places where tomato is grown. In Hawai‘i, TYLCV was first discovered in Wailuku, Maui, and Poamoho, O‘ahu, in November of 2009. It is not known how TYLCV entered Hawai‘i.

Symptoms of tomato yellow leaf curl
The new growth of plants with tomato yellow leaf curl has reduced internodes, giving the plant a stunted appearance. The new leaves are also greatly reduced in size and wrinkled, are yellowed between the veins, and have margins that curl upward, giving them a cup-like appearance. Flowers may appear but usually will drop before fruit is set.

Spread of TYLCV
TYLCV is primarily transmitted by the sweetpotato whitefly (Bemisia tabaci) and the biotype B (or silverleaf) whitefly (Bemisia argentifolii). These whiteflies can acquire the virus in as little as 5 minutes by feeding on infected plants, and they remain infective for life; the virus, however, is not passed on to their progeny. TYLCV is not spread by other whitefly species such as the greenhouse whitefly, Trialeurodes vaporariorum, which is also common in Hawai‘i. TYLCV cannot be spread by seed and is not mechanically transmitted (e.g., by pruning equipment or by touch). Long-distance spread of TYLCV occurs primarily by movement of infected plant material or by wind dispersal of whiteflies harboring the virus.

“At the farm we will scout specifically for plants with these types of symptoms,” Ha wrote in his blog. “But we are very worried that this disease will come to the Big Island. The history of invasive species makes it likely that this disease will get here.”

Visit Richard Ha’s blog for more information and links to CTAHR findings.

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