Managing Bermuda Invasion in Tall Fescue Lawn

Coastal MD, tall fescue 30% Bermuda. Kill whole yard or spot kill? Dig out dead? De-thatch/slit seed? Zoysia better? The expert says transition zone: Bermuda wins summer, fescue wins cool. Fescue doesn't spread, Bermuda increases. Spot kill, aerate/dethatch/slit seed, remove dead mat. Seed good tall fescue when temps drop to low 90s consistently. Repeat yearly reduces problem. Follow-up: "low 90s" in July/August? Actually September. Wait until temps dropping, hit 90s, then seed. Bermuda weakens as fescue grows.