I hope the suggested literature will be interesting and giving answers to your question. However, the short answer is that microorganisms can in principle be applied to any crop. That said, it all depends on the pests and diseases that you want to control. Some are easier to control in this way than others. Hidden insects, like stalk borers, are tough to control, even when using chemical pesticides other than systemic ones.
You will need to provide more details to allow the audience to understand the context. For example, participants here may want to know what microorganisms you are referring. Are they commercial products or something else? What type of pest do you want to control? Is the application to be made in the field or in controlled environment such as greenhouse, aquaponics, etc. If it is a commercial product , let the farmer follow the label instruction and she or he will be good to go.
Application of some microbial pesticide like Bacillus thuringiensis and Beauveria bassiana and Metarhizium anisopliae are pathogenic to silkworms when sprayed on its food plants or sprayed adjacent to silkworm rearing houses. So care should be taken while targeting pests.
According to your question, for handle a farmer a formulated microorganism, you could either produce it as liquid or solid form.
First mass culture your inoculate, as it required. Second, for liquid formulation you could culture your inoculate on inexpensive growth media such as molasses and brewer’s yeast or you could culture it on broth media, half strength media or distilled water (according to the requirement of your microbes).
You could also prepare a solid formulation from your inoculate using agricultural waste materials such as wheat and rice straw, sugarcane bagasse, ground corn cobs, sawdust, rice bran as food base or substrate alone or in combination as carriers for your inoculate.
If you prepared the liquid form it could be easily sprayed or drenched to soil. Solid formulations could be applied with its carrier or could be ground and applied as a powder or diluted with water, sprayed or seed coated (after adding an adherent as molasses or Arabic gum) or drenched.
And if you read the above suggested literature it will give you additional help.