After several experiments, Sevin was found to be another highly effective post bloom thinner. Another chemical, ethephon, was added to the arsenal in the late 1960's. Ethephon is generally used late in the thinning season when prior thinning applications have not worked. Vydate and Accel are two more recent post bloom chemical thinners that are now available to include in a chemical thinning scheme. Post bloom thinners have become popular in part because the risk of spring frosts is reduced.
Growers now have a number of thinning materials of which to choose from.
Often, two or more chemical thinners are combined to increase thinning strength on hard to thin cultivars. Also surfactants and oil can be added to chemical thinners in some circumstances to enhance thinning. Occasionally hand thinning is still used to touch up chemical thinning applications especially on the more valuable fresh market cultivars. Every thinning situation is unique. Blocks of trees are different, varieties are different and every year is different.