Evaluation of different management methods for dodder control (Cuscuta monogyna) on common privet (Ligustrum vulgar) in Mashhad landscape

Background and objectives
Common privet (Ligustrum vulgare) is one of the most important plants in landscapes of Iran. This plant is adaptable to unfavorable environmental conditions, so that is cultivated widespread in urban landscape. Invasion of dodder to Common privet caused problems for landscape management in Mashhad city in recent years. Dodder is an obligate parasite of many plant families and because of the wide geographical distribution, wide range of hosts and inefficient management methods has become the one of the most damaging species of parasite. Because this parasite is very adept and successful from biological and ecological perspectives, a single control strategy is unlikely to provide sufficient economic control. Therefore, various methods of weed management including mechanical, chemical and biological control of dodder on Common privet were evaluated during two years in Mashhad landscape.
Materials and methods
Experiments were conducted in Mashhad landscape in 2010 and 2011. Two sites almost uniformly infested with dodder were selected for implementation of examination during two years. In the first year, experiment was performed in a randomized complete block design with four replications. Treatments included chemical [trifluralin (Treflan 41%), chlorthal-dimethyl (Dachtal 75%) and glyphosate (Roundup 41%)] and mechanical control (mowing and flaming). Mowing treatment had two levels of once and twice mowing. Second year treatments were carried out in a randomized complete block design with three replications that consisted of two isolates of fungi as biological control agents, Roundup and integration each isolate of fungus with herbicide.
Results
The results of first year indicated that application of herbicides significantly controlled dodder, as dodder growth reduced 84-98% than control plots and Dachtal had the most efficient effect. Dry weight of dodder at twice mowing treatment was 16.8 gm-2 that declined 71% dodder development on host vs. control. Once mowing simulated new foliar growth of Common privet that created suitable conditions for growth of remaining dodder on host. However, there was no significant difference with control. Flaming application was also affected in reduction of dodder weight, as the dry weight of dodder in flaming plots was one third of control plots. The results of second year showed that application of fungi isolates individually revealed no significant differences compare to control plots. However, dodder growth showed a significant reduction with using fungi in integrated with herbicide, so that integration of Fusarium sp. and Alternaria sp. with Roundup caused reduction of 83.60 and 81.19% of dodder growth compared to control plants, respectively.
Conclusion
The results of our study suggested that dodder can be controlled with application of integrated management and using non-chemical methods can reduce herbicides use. Treatments of twice mowing, flaming, and integration of Roundup with biological agents were successful in controlling dodder. Using methods that prevent seed production of dodder or reduce seed vigor can reduce weed infestation in subsequent years.