June 2009. A taro problems from Palau: Dasheen mosaic potyvirus or spider mites? First the distorted leaves were thought to have been caused by planthoppers, but there were few in the taro patch, only two or three (sometime none) per leaf. The taro patch is about 1 ha, with very good soil (the mud is knee-deep or deeper). There are several women growing taro in individual plots, and the same symptoms occur in each. The problem has existed for about 3 months. The plants used to be waist high or taller, but now they are only knee-high.

Leaf blight is present, but it is not extensive. The main symptom is the distorted leaves, and small plants. Under the microscope, webbing and frass can be seen along the veins. Now mites are suspected. The corms and roots look normal. Comments were requested.

Members were divided between mites and DsMV. However, the shape of the leaves and their colour is typical of mite damage, a fact that was hard for many members to accept! Many insisted that DsMV was the cause. But the chlorosis seen in the photos is not typical of the disease, and there is an absence of feathering along the veins (although some memebers could see it!) – a typical symptom of DsMV infection. As mites were seen under the microscpe, it is probable they were the cause.

Information on control has already been summarised on PestNet: See www.pestnet.org/Summaries/Crops/Rootstubers/Taro/Mites/Redspidermites /tabid/1271/Default.

Palau also asked if DsMV had been reported from Palau. Is has, on three occasions. See:
http://wwwx.spc.int:8088/pld/report?action=9&hostOrPest=pest&searchString=da
sheen+mosaic&gisLayer=High%2CPLW_pest_all&specie=494&regionalCountryCode=PLW. And the University of Auckland reported that it had recently amplified DsMV sequences from a couple of dried samples, originally collected in 2005. See also: See: http://tinyurl.com/dmvpalau