This week we have experienced much warmer temperatures than the last 2 weeks, with highs in the mid 60s and lows in the mid 40s in the southern part of the state and highs in the 60s and lows in the mid 30s in the norther part of the state. The more spring like conditions in the southern part of the state have push many of our fruit crops to bud break. This upcoming week, temperatures will continue to rise, reaching highs in the mid 60s and lows in the mid 30s in the northern part of the state and highs in the mid 70s and lows in the 40s for the southern part of the state. Insect development is tied to ambient temperatures; thus they will come out earlier if the temperatures are favorable to development (often 50°F is a good threshold for insect development). Get ready for early-season insects to emerge if they have not already done so.

Growing Degree Day (GDD; base 45˚ F) accumulation for the West Madison Ag Research Station (WMARS) is at 86 and is expected to reach 150 by next Tuesday. While at Peninsular Ag Research Station (PARS) they have accumulated 40 GGD and will reach 50 by next Tuesday.

Apples

The warmer weather has pushed bloom development for apple trees. Early cultivars such as Zestar were at late tight cluster, and Honeycrisp transitioning from green tip to tight cluster, and later cultivars such as Liberty and Galas are at green tip in Southern Wisconsin. Plans should be in place for monitoring degree days and early-season insect pest activity. At the Peninsular Ag Research Station (PARS) in Sturgeon Bay early apple cultivars are at green tip and later cultivars at silver tip.

Blueberries

At the West Madison Agricultural Station (WMARS) blueberries the most advanced cultivars were at tight cluster and the later cultivars at bud swell. The warmer temperatures forecasted for early next week will results in plants moving quickly into bloom.

Strawberries

Leaves have already emerged from crowns in southern Wisconsin, so winter mulches should be removed to avoid harvest delayed and decreased yield.

Grapes

Vines are just starting to move. At the research vineyards in WMARS all cultivars are still dormant, but some signs of bud swell were visible in LaCrescent and Marquette. For those growers that have delayed pruning, bud break will be delayed. At WMARS we did a long pruning and left 5 to 6 buds per spur to delay bud break. We will do a final pruning to 2 buds per spur in early May once the risk of a spring frost is minimal. Make sure to start scouting for grape flea beetle and possibly cutworms feeding on buds. At PARS all grape cultivars are still at tight bud.

This article was posted in Apples, Berries, Grapes, Insects and tagged apple phenology, Apples, Blueberries, Fruit Phenology Update, gdd, grape phenology, Grapes, Growing Degree Days, PARS, Strawberries, WMARS.