STUDIES ON THE PHYSICAL AND CHEMICAL CONTROL OF APPLE PROLIFERATION IN TREE NURSERIES AND BEARING ORCHARDS
The wide distribution of apple proliferation and its high rate of appearance at the age at which the trees bear fruits associated to a decrease of the biological potential, resulting in serious economic implications, prompted the present studies.
- Physical control 1.1. Hot air treatments at 38°C applied for 2 days to 3 year-old-diseased trees had a radical therapeutic effect, the mycoplasma present in the buds fit for grafting being inactivated. The heat probably induced a hormonal disorder, since the proportion of set grafted buds was lower than in the untreated check; 1.2. Hot air treatments at 50°C applied for 2 hours to cuttings had a total therapeutic effect since 55% or the buds were set; 1.3. Immersion of the branches in hot water at 50°C for 2 hours was totally harmful; 1.4. X- and UV-rays determined intermediate effects.
- Chemical treatments 2.1. The most effective low-toxicity chemotherapeutants were in decreasing order : Pyoctamin 1%0, Chloramphenicol 1%0, Penicillin and Tetracyclin with a therapeutic effect of 100% and rate of successful grafting of 55%, 44%, 35% and 20%, respectively. Streptomycin proved totally phytotoxic; 2.2. Four out of the 9 chemicals tested for 2 years in fruit bearing orchards on the same trees showed a wide range of activity, systemic and curative effects, and high translocation ability, e.g. Benlate 0.1%, Derosal (Hoe 17 411 OF) 0.075%, Topsin M 0.1% and Kasumin 0.2%.The differences between the rate of disease differentiation of the variants receiving chemical treatments and the untreated check were highly significant negatively; 2.3. Mineral fertilization with NPK applied in 16 quantitative variants did not attenuate the disease but, on the contrary, enhanced the activity and concentration of the pathogen in the host plant.
Gheorghiu, E. (1976). STUDIES ON THE PHYSICAL AND CHEMICAL CONTROL OF APPLE PROLIFERATION IN TREE NURSERIES AND BEARING ORCHARDS. Acta Hortic. 67, 149-158