Source-sink interactions lead to atypical reproductive stage phosphorus deficiency symptoms on the upper foliage of Capsicum annuum and Chrysanthemum ×morifolium

•Phosphorus deficiency onset upon flowering leads to upper leaf deficiency symptoms.•Upper foliage and flowers compete for limited phosphorus supply.•Plants exhibit preferential phosphorus allocation to reproductive tissues.•Developing upper foliage is deprived of phosphorus, causing symptom development.