We planted a row of twenty Siberian pea shrubs from bare root stock this spring. Planting is in rural Parker, CO. They were drip watered daily for two month, then cut back this past month to watering every third day.. They leafed out quickly and seemed great. One of them has yellowing leaves. Most of the leaves on the plant are yellow, the other plants have some yellow, but most are healthy green. The yellowing one seems to be insect free, at least is no infeasted. The soil is heavy with clay. None of them have had ant soil additives other than some peat planting soil when planted in early June. Any suggestions?