In Central Alabama, chill hour requirements of most peach cultivars were satisfied early during dormancy in 2017-2018 dormant season. As a result, flower buds began to break dormancy after a significant warming trend in February. This early bud development resulted in exposure of developing flower buds to several low temperature events in March and April of 2018 causing severe flower/fruitlet thinning in many peach varieties.
Damage to the crop was assessed by counting the total fruit number on 3 – 5 trees (or any number of available trees below this range) of a cultivar in the peach cultivar block at Chilton Research and Extension Center (CREC). The average number of fruit for a cultivar was determined by dividing the total number of fruit of a group of trees by the number of trees in a group. Prior to counting, an assessment of the general fruit size of a particular cultivar was made. Fruit significantly below this established size category were not included to insure that only fruit likely to develop were counted.
Average fruit number per tree was the highest in 'Julyprince' (541) followed by 'Autumnprince' (426) and PF 24 CH (322). Sixty-eight percent of trees had an average crop load below 100 fruit per tree. Fourteen percent of trees had an average crop load above 200 fruit per tree, while 39% had an average crop load of 70 fruit per tree and below.
As expected, most crop thinning occurred among the early season varieties while the largest crop loads occurred in mid to late season cultivars. In terms of chill hour requirements, peach cultivars that required 800 to 850 chill hours had the highest crop load while cultivars with the lowest average crop loads were in the 425-650 and 700-750 chill hour ranges. Looking back at the assessment of bloom survivability conducted earlier in the season at CREC (See "Assessment of Peach Flower Bud Survivability in Chilton County" in the Alabama IPM Communicator March 27, 2018, www.aces.edu/agriculture/insects-diseases-weeds-pests/IPMCommunicator/), percent survivability was the highest in varieties that require 850 to 1,050 chill hours. Cultivars that require the least chill had the lowest percent survivability, which was demonstrated among the low chill varieties in average crop load per tree.
Crop load was reported to be lower than expected overall in peach operations in the county. Growers with the benefit of wind machines or access to helicopters for freeze/frost protection produced substantially more fruit per tree. One observation often made among growers was that fruit was larger than normal due to the excessive natural thinning. Another observation was the earliness in harvest. Harvests this year appeared to be as much as two to three weeks earlier than normal/historic averages. If this trend continues, the peach season in Chilton County should be completed by the end of August.
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