## 3 Discussion  
The re-isolation of the _B. bassiana_ from the leaf tissue of 50% of fungus-inoculated plants demonstrated that there was moderate colonization of the tissues of _V. vinifera_ plants after experimental inoculation. The colonization of potted grapevine plants by endophytic fungi has been reported previously [9]. It is worth mentioning that successful colonization is influenced by factors, such as fungal species, fungal strain, and host, etc., [28; 29; 30]. Despite successful colonization, interestingly, the colonization by _B. bassiana_ of the grapevine tissue did not translate to any noticeable increase in plant growth. Inconsistent effects of fungus on plant growth parameters have been reported. [PERSON] et al. [30] did not observe a major difference in plant growth following inoculation of banana (_Musa_ spp.) with endophytic _B. bassiana_ strain compared to the control treatment. However, in other similar studies, endophytic _B. bassiana_ induced higher growth in onion and tomatoes [31; 32]. The growth promoting effects of _B. bassiana_ is probably dependent on the availability of nutrients in the growth medium. The absence of visible effects on the growth parameters assessed is seemingly consistent with the no effect of the fungus on the tissue macronutrients (nitrogen (N), phosphorus (P), and potassium (K)) contents observed in this study--plant growths are known to be correlated with these primary nutrients [33]. Fungal microbes are generally known to promote plant growth by facilitating nutrient resource acquisition from the environment. In the current study, the plants were exposed to a constant and adequate supply of the required nutrients, especially nitrogen, and this might have reduced any influence the fungus might have had on the supply of nutrients to plants. According to [PERSON] and [PERSON] [34], the mechanisms by which _B. bassiana_ increases plant growth should be investigated further. The two nutrients that were found to be significantly influenced by fungal inoculation were calcium and magnesium. These nutrients are important to plants for varying reasons. Calcium is an essential element for the development of new plant tissues; it strengthens cell walls and promotes cell elongation [35]. It is also known to help protect plants against pathogenic fungi and bacteria. Magnesium is a building block for chlorophyll, which is important for the process of photosynthesis. It also activates certain plant enzymes needed for growth and contributes to protein synthesis [36]. They can also influence secondary metabolite production. For example, supplementing plants with Ca has been proven to enhance total protein content, as well as phenol and flavonoid content [37]. Although little is known about the role of Mg in plant secondary metabolism, Mg deficiency is known to increase phenolic compounds and putrescine accumulation in cells [38]. The key finding here is the clear association between the number of volatiles detected and the fungus treatment (Table 5). There are many plausible explanations for the higher volatiles in the fungus-treated plants: perhaps this is mediated through calcium and magnesium uptake [37; 38], maybe it is due to direct production of secondary metabolites by fungi [39], or better still, it is as a result of plant defense reaction in the presence of the fungus in the tissue [40]. Interestingly, naphthalene was detected in the fungus treated plants in this study. Naphthalene is toxic to humans, is a potent insecticide and an insect repellent [41; 42], and is the main active ingredient in mothballs. In a separate study, _B. bassiana_ released volatile organic compounds, including diisopropyl naphthalenes [43]. Earlier, [PERSON] et al. [24] demonstrated that _Muscodor vitigens_, an endophytic fungus, can also produce naphthalene and further showed that the insect repellent activities of the fungus against adult stage of the wheat stem sawfly, _Ceplus cinctus_, was comparable to authentic naphthalene.