6.143
STUDIES ON PUCCINIAABRU PTAVAR.PARTHENIICOLA A POTENTIAL MYCOHERBICIDE FROM INDIA.
STUDIES ON PUCCINIAABRU PTAVAR.PARTHENIICOLA A POTENTIAL MYCOHERBICIDE FROM INDIA.
G BAGYANARAYANA 1 , C MANOHARACHARY 1 AND P. RAMESH 1 1 Department of Botany, Osmania University, Hyderabad - 500 007, A. P., India.

Background and objectives /b>
Partheniumhysterophorus a pernicious and abnoxious weed was first reported in 1956 from India and has spread to almost all parts of India in an alarming proportion [1]. Losses are caused by Parthenium both to Agriculture and Forest plants. lt is also known to cause contact dermatitis. Conventional methods to control parthenium weed has various limitations. There-fore, a search was made for a safe locallyavailable fungal pathogen. This resulted in the collection of Puccinia abrupt avar. partheniicola from the forests of Andhra Pradesh, lndia for the first time. Studies were made to know the morphology of spore forms, effect of temperature and humidity on germination of urediniospores. Cross inoculation experiments were conducted to know the host range and specificity.


Results and conclusions
Periodic observations of < i > Puccinia abrupta var. partheniicola < /i > during different seasons of the year both in field and green house conditions revealed uredinial stage only. Underfield conditions maximum infection wasfound between December - January and minimum in April -July. The uredinia were subepidermal, rupturing the epidermis at maturity, exposing brown spore mass. Urediniospores pedicillate, with 3 germ pores, 2 sub-equatorial, 1 supra-equatorial. The percentage of urediniospore germination on DWA was maximum between 1 5 201 and a humidity of 70 - 90%. On leaf surface the entry of the germ tube was through stomata within 4-7 hrs after germination. A sub-stomatal vesicle was formed after 7-11 hrs. Host specificity tests of the pathogen conducted on certain hosts of Asteraceae, Lamiaceae and Papilionoideae which were naturallygrowing nearthe vicinityof the infected parthenium plants did not result in any infection and rust symptoms.


This investigation revealed the indigenous occurrence of P. abrupta var. partheniicola in India. The rust appears to be perpetuating through repeated generations of urediniospores. Evans [2] made a similar observation. The urediniospores require low temperature, and high humidity for their germination. The pathogen is highly host specific being able to infect parthenium plants alone. Therefore can be used as a safe bio-control agent against parthenium under Indian conditions.


References
1. Aneja AK. 1 991. Botanical Researches in India, PP. 258-269. 2. Evans H C. 1987. Transactions of British Mycologica1 Society 88, 105 - 111.