Yellow leaves can be due to a few different issues.
Nematodes cause the leaves of the strawberry plant to yellow. Other symptoms include stunted growth, wilting, and fewer berries.
Verticillium growth first exhibits itself in the older leaves of the plant, turning yellow and brown between the veins of the strawberry plant leaves. Verticillium wilt takes root best at the onset of hotter, drier temperatures, when the strawberry plant may become more stressed due to inconsistent watering.
Verticillium growth first exhibits itself in the older leaves of the plant, turning yellow and brown between the veins of the strawberry plant leaves.
Watering issues; too much or too little. Soil should be moist; never soggy or overly dry.
When there is poor soil nutrition, strawberry plants develop yellow leaves as an indicator they're not receiving proper nutrition.
You mention manure; but manure needs to be properly composted to be used in the garden.
A soil test can help you determine if you have too much or too little nitrogen and other nutrient issues. Your County Extension Office can help with a soil test.
These articles will help you.