I would suggest you to have consistant reference material when researching biotic stress. If you are analyzing different varieties/cv the biotic stress might be milder in some than other, so always having a good reference material might help you. A good experimental design might also help were the condition are optimal for your experiment and you might avoid inconsistant data.
I would suggest you to have a look at previous research, at the following links:
https://www.intechopen.com/books/abiotic-and-biotic-stress-in-plants/biotic-and-abiotic-stresses-in-plants Article Effect of Abiotic and Biotic stress on the Plant
Nowadays, we have the novelest weapon, CRISPR system, to precisely knockout a specific gene in the plants and induce resistance to biotic stress, such as fungus-, bacteria-, parasitic weed-resistance.
See paper below:
S3 Biotech. 2017 Aug;7(4):239. doi: 10.1007/s13205-017-0870-y. Epub 2017 Jul 12. Genetic engineering strategies for biotic and abiotic stress tolerance and quality enhancement in horticultural crops: a comprehensive review.