## 1 Introduction  
The process of pollination involves the transfer of pollen grains from the anther, the male portion of a flower, to the female part (stigma) of the same or another plant. There are two types of pollination: (i) self-pollination (autogamy), in which pollen is deposited on the stigma of the same or another flower on the same plant; and (ii) cross-pollination (allogamy), in which pollen is transferred from one plant to the flower of a genetically different plant or cultivar. Walnut trees are self-compatible, but they require cross-pollination with another walnut tree to produce nuts due to being protandrous, meaning that the male flowers mature--release pollen--before the female flowers become receptive, and pollen shedding occurs before female bloom begins, or being protogroups, meaning that the female flower begins opening--become receptive--prior to pollen shedding. Cross-pollination involves transferring pollen from the male flowers of one walnut tree to the female flowers of another. This can occur naturally, with the help of the wind (wind-blown pollen) or insects such as bees, or artificially through the process of hand pollination [1]. On walnut trees, the pollen is produced in catkins, which may also be colonized with _Xanthomonas arboricola_ pv. _juglandis_, the causative agent of walnut blight disease [2; 3]. Mainly the disease can affect the leaves, stems, and nuts of the tree, leading to reduced yield and poor-quality nuts. _Xanthomonas arboricola_ pv. _juglandis_ is primarily spread by water, either through rain or irrigation, and can be more severe during warm and wet weather [4; 5]. Once the bacterium enters the tree tissues, it can survive and spread within the tree through the sap. To prevent and control _X. arboricola_ pv. _juglandis_, farmers can use a combination of cultural and chemical control measures. This may include removing infected plant material, managing irrigation practices to reduce water on the foliage, and applying copper-based fungicides during the dormant season or at the first signs of infection. Here, it is important to note that the overuse of chemical control measures can lead to the development of resistant strains of the bacterium, so it is important to use a holistic approach to disease management that incorporates a variety of methods. Additionally, early detection and rapid response to infected trees can help to limit the spread of the disease to other trees in the orchard. Research has shown that inoculum of _X. arboricola_ pv. _juglandis_ is also disseminated through pollen [3; 6]. This evidence-based early detection of developmental-behavioral problems from primary infection of _X. arboricola_ pv. _juglandis_ in symptomless plant materials, such as catkins and pollen, should be considered besides that in symptomatic materials (leaves, fruit, and other plant debris). Pathogenic bacteria and pollen are two distinct biological entities that are not directly related to each other. While pathogenic bacteria and pollen are not directly related, they can sometimes interact in certain situations. For example, pollen can sometimes serve as a carrier for pathogenic bacteria. Pollen of _Actiidia_ spp. is a good substrate for _Pseudomonas syringae_ pv. _actinidia_ colonization, survival, and a pathway for its spread [7]. Therefore, pollen may be a conduit for the spread of _P. syringae_ pv. _actinidae_ and kiwifruit bacterial canker [7]. Further, pollen dispersal has been presented for _Erwinia amylocora_ of pome fruit [8] and for _X. arboricola_ pv. _juglandis_ of walnut [9; 10]. Moreover, pollen was recognized as a possible pathway for _X. arboricola_ pv. _juglandis_, although further studies were suggested to confirm if pollen could spread the pathogen [3]. Viable pathogenic bacteria such as _X. arboricola_ pv. _juglandis_ have often been isolated from pollen, and infected pollen also represents a potential route of introduction into healthy walnut groves even in case of mechanical pollination [3; 6]. Walnut cv. [PERSON] and cv.