Azaleas

By the aid of the processes described Tunmann claims to have discovered the resinogenous layer in all the plants examined by him. In the course of his investigations he was able to determine various typical forms of the layer. These he divides into three principal types the rod-type (Viola Fraxinus, Alnus), the vacuola-type (Salvia.Hyssopus), and the mesh or grille-type (Rhododendron, Azalea). 

Ironically, coffee does need relatively acidic soil, with pH between 5 and 6. Conifers and shmbs such as azaleas and rhododendrons thrive on soils with this acidity, as do tea, potatoes, rice, and rye. The vast majority of crop plants, including most vegetables, need soils just on the acidic side of neutral, pH between 6 and 7. Only a few crops—barley, sugar beets, cotton, and sugarcane—like soils on the mildly basic side, between pH 7 and 8, and only desert plants can cope with soils whose pH is greater than 8. 

Bacci E, Cerejeira MJ, Gaggi C, et al. 1990b. Bioconcentration of organic chemical vapours in plant leaves The azalea model. Chemosphere 21 525-535. 

Susceptible plants Pear, raspberry acid-lovers such as camellias and azaleas growing on alkaline soils, but any type of plant can be affected. 

The fungicide Carboxin has received some study, but with varied results. A 0.43 mM solution gave protection at 5-10 days in white bean, a 0.36% spray gave no protection to pinto or tempo bean, and a 0.01% spray increased injury to azalea. Soil applications of Carboxin were generally more beneficial, but results were still varied. A Carboxin soil amendment was phytotoxic to tobacco and pinto bean, although protection was noted in pinto bean. Pinto and tempo bean were protected from oxidant for 36-40 days after a soil amendment with Carboxin... 

Moyer, J. W., H. Cole, Jr., and N. L. Lacasse. Suppression of naturally occurring oxidant injury on azalea plants by drench or foliar spray treatment with benzimidazole or oxathin compounds. Plant. Dis. Rep. 58 136-138, 1974. 

Azalea japonica A. Gray A. mollis Blume A. pontica var. sinensis Lindl. Yang Zhi Zu (Azalea) See Rhododendron sinensis ... 

Rhododendron molle (Blume) G. Don Ba Li Ma (Chinese azalea, yellow azalea) (fruit) Rhomotoxin.37-144 This herb is toxic. Treats tachycardia, palpitations, hypertension. 

Rhododendron mucronatum G. Don Bai Du Juan Hua (white azalea) (flower) Essential oil, germacrone, farreol, grayanotoxin, gossypetin, azaleatin, 5-methyl kaempferol, 5-methyl myricetin, syringic acid, dihydroquercetin, coumarins, phenolic acid, p-hydroxybenzoic acid, protocatechuic acid, vanillic acid.48 Treat cough, asthma, headache, respiratory infection. 

On ornamental plants CCC is applied to azaleas, geraniums, and hibiscus (Hibiscus sp.) to make compact plants, and to poinsettias to reduce stem height and increase the red color of the bracts. A considerable amount of work has been carried out on cereals with CCC to reduce stem length and inhibit lodging. In Europe, the effect of CCC on shortening the culms of cereals is dependent upon the genotype. It has been demonstrated that the effect is as follows wheat > triticale > durum wheat > rye > oats > barley > corn = millet = rice (37). In barley, culms are initially inhibited but later the plant overcomes the inhibition (37). This has been attributed to poor assimilation, translocation, and rapid breakdown in wheat (38). 

Off-Shoot-O. The methyl esters of the Cg—C12 fatty acids (40) are collectively sold under the name Off-Shoot-O and are closely related to 1-decanol, the fatty alcohol sold to control axillary shoots in tobacco. The material is a contact-type chemical used to pinch ornamental plants such as azaleas, cotoneaster, juniper Juniperus sp.), privet, rhamnus, and taxus (Taxus sp. sp.). As a result of treatment the shrubs become bushier. The mode of action is by plasmolysis of the young, sensitive tissues. Therefore, application timing may be critical. 

The family is cosmopolitan with the exception of deserts. It contains many of our familiar ornamentals (rhododendron, azalea, etc.), fruits (blueberries, cranberries, and relatives), briar, and wintergreen. 

Current plant-air partitioning data are limited to a very few species, namely azalea leaves and rye grass and a few data for spruce needles. The plant-water partitioning data used to develop methods also are limited to isolated cuticles from just four plants and macerated barley leaves. We thus cannot expect that currently available methods adequately account for the interspecies variability in partitioning. 

Bacci, E., M.J. Cerejeira, C. Gaggi, G. Chemello, D. Calamari, and M. Vighi- 1990. Bioconcentration of Organic Chemical Vapours in Plant Leaves The Azalea Model. Chemosphere 21, 525-535. 

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