Cause Iris mild mosaic virus (IMMV) and iris severe mosaic virus (ISMV) are problems for bulbous iris; iris fulva mosaic virus (IFMV) is a problem for rhizomatous irises. All are in the potyvirus group. Transmission, by aphids, is nonpersistent. Bean yellow mosaic virus (BYMV) and narcissus latent virus (NLV) have also been found. Less commonly found are cucumber mosaic virus, broad bean wilt virus, and tobacco ringspot virus.
Symptoms On bulbous iris, IMMV-infected plants may be stunted with yellowish streaks on leaves and dark, teardrop-shaped markings on white, blue, or lavender flowers. Clear, feathery markings may develop on yellow flowers. Iris are more severely affected if simultaneously infected with IMMV and ISMV, BYMV, or NLV. Symptoms also are more pronounced during cool, wet weather and on young foliage.
Iris fulva hybrids infected with IFMV have a mild mosaic, sometimes with leaf malformation.
Cultural control
- Plant pathogen-free stock.
- Rogue all diseased plants.
- Plant resistant or symptomless cultivars.
- Controlling aphid vectors is not effective.
References Barnett, O.W. 1986. Iris fulva mosaic virus. AAB Descriptions of Plant Viruses, No. 310. Wellesbourne, Warwick, U.K.: Association of Applied Biologists.
Brunt, A.A. 1986. Iris mild mosaic virus. AAB Descriptions of Plant Viruses, No. 324. Wellesbourne, Warwick, U.K.: Association of Applied Biologists.