Don’t expect it for the 2025 season in Illinois but look for a new apple and pear thinner from ADAMA under the trade name Brevis SG possibly in 2026.  The company’s U.S.  launch will start with Washington state this year, then expand in 2026.  The active ingredient, metamitron works differently than hormonal thinners.  It thins fruit by temporarily stressing the tree through inhibition of photosynthesis at PSII without interacting with plant hormone regulation...yes, it is a group 5 herbicide.  But it has many years of research and use overseas, proving its usefulness and safety.

A carbohydrate model (NEWA) should be used as a predictive tool, using local temperature and solar radiation data, combined with the apple cultivar and fruitlet size to determine days when to get the best thinning result and when there is a risk of over-thinning. The application window will be late petal-fall (6-7 mm fruit) until 16-20 mm.