Infrastructure means the basic structure of an organization or system. A company's infrastructure would include all the fixed assets, i.e., the building, equipment, machinery and tools required to manufacture their product. Although people are not fixed assets they would be included in the company's infrastructure too.
Rarely a serious problem. Look-alikes: Jumping oak gall, tubakia leaf spot, oak leaf blister, other fungal leaf spots. Jumping oak gall Brown leaves appear on trees in the white oak group in late spring. Severe infections may cause the leaves to turn black, curl up and fall. On the underside are brown galls with the larva of a small wasp inside.
Citrus trees lose leaves after you water them once they have dried out. If your citrus tree is getting too much water, meaning that the drainage is poor, the leaves will yellow and then fall off. If your citrus tree loses all of its leaves due to over or under watering, do not despair.