Burnt / turned up rusty leaves

[JiggaWhat]

Three or four weeks into flowering and the top leaves have little rust spots, are turning up, and are a little crispy around the edges. Have been feeding and watering every three days with VERY dilute nutrient solution and deionized water. the decision has been made to cut back on feeding and water more frequently but with less water until the problem resolves itself. any other suggestions?

Thanks.