Imbalances in the soil especially when pH and nutrient levels are not in the optimum range can cause a host of problems. The deficiencies are more acute in container or hydroponic plants than in soil. Nutrient availability is dependent mainly on pH but also on the inter relationship between other elements in the soil.
The plants I have the most problems with are the ones that I have growing in containers especially with reused soil. The following links have visual guides to symptoms of nutrient deficiencies and excesses.
Nutrient Deficiencies of Cucumber
https://www.haifa-group.com/cucumber-0/ ... s-cucumber
Nutrient Deficiencies in Tomato
https://www.haifa-group.com/online-expe ... deficiency
Nutrient Deficiency of Peppers
https://www.yara.co.uk/crop-nutrition/s ... es-pepper/