Similar to previous summers with adequate rainfall, Kentucky bluegrass has turned an off-color yellow in the last few weeks. We are still unsure of what could be causing this. What we do know:
· Only the young leaves are yellow, so it is probably not related to nitrogen or other nutrients mobile in the plant. However, iron deficiency could explain the symptoms because Fe is relatively immobile in the plant.
· There are no obvious lesions present so it is not mediated by above-ground diseases.
· We do not see it in tall fescue, perennial ryegrass, and some cultivars of Kentucky bluegrass.
· We see it when soil temperatures are at their seasonal highs.
· We see it almost exclusively on irrigated turf and most frequently during wet summers.
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