When should I sprinkle, and when should I flood?
This will depend if you have harvested and removed the irrigation pipes or not. If you have not harvested yet and there is a potential frost, I would use the sprinklers over flooding. Right before harvest, flooding the entire bed might affect fruit quality to a greater extent than sprinkler irrigation.
If you have already harvested and returned pipes to the bed, then it will depend on how low temperatures will drop. From our cold-hardiness studies (done on Stevens and HyRed), by early October, buds are hardy to about 10° to 5° F, by early November from -5° to -10° F and by December -15° to -20° F. This is a generalization and it will depend on the temperatures experienced during the fall—the warmer the fall, the longer it will take for those buds to gain cold hardiness, and the opposite is also true. So, going back to the question of using sprinklers versus flooding after harvest, I would say flooding is safer as it will provide better protection.
If I have damaged vines from last winter (or any other damage), should I encourage that bed to go dormant faster? Should I harvest it earlier than I otherwise might have?
Always try to harvest as early as possible, as fruit quality only declines once the fruit has achieved the color needed for harvest. In terms of the relationship between harvest and entering dormancy, I don’t think we have a good understanding how the timing of harvest will affect the vines entering dormancy. In other fruit crops, such as grapes, we know that buds can gain cold hardiness even when they still have fruit hanging from the vines, and I would expect something similar to happen in cranberries. Most probably, one of the cues for the vine to enter dormancy has to do with photoperiod. Shortening of daylight is a key for the vines to enter dormancy, as well as colder temperatures (close to freezing) during night time. If you have vines that experienced damage last winter and you are encouraging recovery, I would definitely harvest as soon as the fruit has gained the required color and then make sure you are irrigating the beds if the need it during fall. I would also recommend a very low doses of nitrogen fertilization (not more than 5 units of N) that will encourage new growth the following spring. This low rate of fall fertilization will not affect the vines entering dormancy or their cold hardiness levelsThis article was posted in CCMJ, Cranberry and tagged Allison Jonjak, Amaya Atucha, cold hardiness, Cranberries, cranberry, dormancy, flood, Harvest.