Aster yellows

Cause Aster yellows. For more information, see "Leaves greenish yellow growth poor" on raee 19. 

Roots misshapen and covered with numerous hairlike roots. Causes Root knot nematodes aster yellows. Root knot nematodes cause tiny round swellings on side roots. Prevent future root knot nematode problems by applying chitin or parasitic nematodes to the soil before planting. 

Roots infected with the disease aster yellows are small, woody, hairy, and taste bitter. See Young leaves yellow and dwarfed growth bushy above for controls. 

Leaves and flowers greenish yellow, distorted new growth spindly. Cause Aster yellows. Feeding leafhoppers may transmit this disease. There is no control for aster yellows. Remove and destroy infected plants do not compost them. Prevent the disease spread by controlling sucking pests such as leafhoppers and aphids. 

Young leaves are dwarfed, curled, or twisted. Cause Aster yellows. There is no cure for infected plants destroytthem. Control leafhoppers because they spread this disease. See Leaves pale plant stunted above for leafhopper controls. 

Sage is normally quite trouble-free. Aster yellows can cause dwarfed, abnormally colored leaves and bushy growth. Destroy infected plants, and control leafhoppers and other sucking insects that spread diseases. Tan or red blisters on leaves are caused by rust. Destroy infected leaves and avoid wetting leaves to prevent its spread. See the Herbs entry beginning on page 116 for other possible problems. 

Some diseases once thought to be caused by viruses, such as aster yellows, are now known to be caused by mycoplasma-like organisms (MLO). Mycoplasmas are extremely small, somewhere in size between common bacteria and viruses. Although generally grouped with bacteria, mycoplasmas differ trom bacteria be cause they lack a cell wall. Each mycoplasmal cell is enclosed in a soft membrane. But mycoplasmas and MLOs, like bacteria, respond to antibiotics. They are also similar to viruses in that they are transmitted by insects. 

Plants Affected A wide range of woody and herbaceous plants. Aster yellows affects many plants, including carrots, lettuce, tomatoes, China asters, and gladiolus. Elm yellows (also known as elm phloem necrosis) attacks several species of elms. 

Aster and (see Aster yellows) Fusarium (see Fusarium yellows) Ulmus and, 381 Yew. See Taxus Yucca. 252... 

Bupleurum falcatum (Chai hu plants) is an important tonic herb for the liver and circulatory system of humans and can alleviate hepatitis. Chang et al. (2004) reported aster yellows phytoplasma associated with Bupleurum falcatum plant in Canada. Diseased plants showed resetting, proliferation of auxiliary shoots at the nodes of the stem, witches - broom, virescence and phyllody symptoms. 

Alignment of the intergenic spacer region 16S-23S rDNA sequences of Bupleurum falcatum phytoplasma (AY394856) showed a high degree of homology with DNA sequences of Florida periwinkle virescence and western aster yellows phytoplasmas in parsley and Chinese aster. 

Nucleotides 63, 67, 71, 96 and 197 represented the only sequential differences between these phytoplasmas and the chai hu phytoplasma. The results suggest that the Bupleurum falcatum phytoplasma belongs to the aster yellows subgroup I-A. 

The bulb of Lilium plant is antiinflammatory, diuretic, emmenagogue, emollient and expectorant. They are used to relieve heart diseases, pain in the cardiac region and angina pectoris. They are used to treat coughs, sore throats, palpitations and boils. The flowers are carminative. They are used to strengthen the eye-lid muscles and are commended in the treatment of myopic astigmatism. It is not clear when aster yellows type disease was... 

Valerian sp. (Valerianaceae) Aster yellows disease Canada Khadhair et al. (2008)... 

Apocynaceae) Maryland aster yellows in periwinke Yellowing Lee and Davis (1992)... 

American aster yellows in periwinkle Yellowing Seemuller et al. (1994)... 

Aster yellows phytoplasma is transmitted to chai hu plants from other infected plants in Alberta by aster leafhoppers Macrosteles sp.). These insects were commonly found associated with various economical crops in Alberta (Khadhair et al., 1997c). They are naturally capable of feeding on a wide range of plants and are highly mobile (Chang et al., 2004). 

Rose proliferation and stunting as well as rose leaf curl and shoot dieback symptoms in rose cultivars were associated with aster yellows phytoplasmas (AY, 16SrI-B). It was also found, that two rose cultivars, with shoot proliferation or flower proliferation symptoms were infected by phytoplasma classified to apple proliferation group (16SrX-A) (Kaminska and Sliwa, 2004). Jarausch et al. (2001) reported the occurrence of European stone fruit yellows phytoplasma (16SrX-B), Candidatus phytoplasma prunorum and rubus stunt (16SrV-E), in asymptomatic Rosa canina plants surrounding peach orchards. 

Arocha, Y., Pinol., B., Picomell, B., Almeida, R., Jones, P. and Boa, E. (2006b). Basil little leaf a new disease associated with a phytoplasma of the 16SrI (Aster Yellows) group in Cuba. Plant Pathol., 55 82. 

Carling, D.E. and Millikan, D.F. (1978). Banded filaments associated with the aster yellows MLO in Vinca rosea. Canadian Journal of Microbiology, 24 1417-1418. 

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