Dodder is a parasitic weed that causes a lot of damage to citrus production in the south of Kerman province, Iran. Introducing cultivars which tolerant to this parasite can be considered a very effective step in controlling it. Therefore, to evaluate the tolerance of seven important citrus species to dodder, an experiment was conducted in a randomized complete block design with three replicates in greenhouse conditions for two years (2016–2017). In this experiment, the reaction of orange, local, and Kara tangerine, grapefruit, Valencia orange, local orange, and lemon seedlings to dodder infestation was investigated. The infestation was done artificially by placing 10 dodder’s thallus on the seedlings of each of the mentioned species. After the successful establishment of the parasite (during 4 months), chlorophyll content, number of stems on citrus species shoots, number of capsules in infested seedlings, and seed weight on each seedling were measured and recorded. The results of this study revealed that different species of citrus showed very different reactions to the presence of dodder so that these species can be based on the success rate of its attachment to them into tolerant and sensitive species. According to the results, Valencia oranges and Bitter orange were tolerant to dodder, but lemon and tangerines (local and Kara) showed high sensitivity. A cross-sectional of plant tissues showed that concerning anatomic view, there was no difference in haustorium penetration between the different citrus species. As a result, it is recommended to use physiological, genetical, and biochemical analysis to distinguish the differences.
