What leaf color and pattern would indicate a potassium deficiency in cool-season grasses?

• A. Marginal leaf scorching and tip browning beginning on older leaves, with interveinal chlorosis in some cases
• B. Uniform green color with no symptoms
• C. Interveinal chlorosis only
• D. Red-purple tint on new growth

Answer: (A)

Potassium is mobile in grasses, so deficiency symptoms first appear on older leaves as they borrow K for new tissue. The hallmark is marginal leaf scorching and tip browning along the edges of those old leaves, often starting at the tips. In more severe cases you may also see interveinal chlorosis, where the area between the veins yellows while the veins stay green. This pattern—older leaves with burnt margins and brown tips, sometimes with slight interveinal yellowing—best reflects potassium deficiency in cool-season grasses. Uniform green means no issue, chlorosis only points to other nutrients (like iron or magnesium), and a red-purple tint on new growth suggests different problems (often phosphorus).