Last week at the mini clinic I talked about cold hardiness of buds during this time of the year and addressed some of the concerns many of you had about potential damage during this week’s cold temperature forecast. Here’s a summarize of my recommendations:

• The weather we have experienced so far this spring has followed the general pattern of spring temperatures in Wisconsin. Last year, we had very warm temperatures in late March that pushed the vines out of dormancy faster than expected followed by low temperatures that might have resulted in the overall lower than expected yields we had in 2021. This 2022 spring, temperatures have raised at a slower rate, and even though we have had warm days with high >70 ˚F, the minimum temperatures have mostly stayed below the freezing point and 40 ˚F.
• Our cold hardiness studies concluded there is a significant loss in bud cold hardiness during the spring period when buds resume their growth and new vascular tissue is developed, even when there are no visible changes to the bud’s appearance. This shift in bud cold hardiness usually happens after 5 to 7 consecutive days of exposure to daily minimum temperature over 40 ˚F. The initial shift in bud cold hardiness goes from tolerating temperature below 0 ˚F to incurring damage when temperatures range between 10 to 15 ˚F.
• Based on the weather records for our growing regions, I would anticipate that at this point buds will be able to withstand minimum temperature of up to 15 ˚F. However, our studies did not consider windspeed, so if you still have frost in the ground you might want to flood and protect mostly the leaves (since buds should be hardy enough to withstand the forecasted temperature) from desiccating and dropping before bud break.

Fertility recommendations:

During the mini clinic last week there were several discussions about leaf damage and severed upright from the hailstorm experienced a couple of weeks ago in some growing regions. I know that many growers get anxious when looking at uprights that have dropped leaves, but there isn’t much we can do about it at this point. Many growers might be tempted to apply fertilizers earlier than normal to increase fruit set and vegetative growth. My recommendation is not to apply extra fertilizer to the vines since this will not help them during this early stage. The best you can do is to make sure you are not stressing the damaged vines so they can use all the reserves they have left to push new growth and flowers. One recommendation would be to avoid flooding the beds that have severe leaf damage, because flooding results in less reserves available for the upright and fruit to grow while new leaves are developing. If possible, skip the insect flood that is done later in the spring when temperatures are warm. Stress to vines that have experienced damage will be intensified if they are flooded during warm temperatures.

The price of fertilizer is outrageous this season and increasing nutrient application before bloom will not result in faster vine recovery from the hailstorm damage nor will it get the vines to bloom faster. Save yourself some money and wait to fertilize until you see fruit set.

This article was posted in Cranberry and tagged Amaya Atucha, cold protection, Cranberries, early spring, fertilization, fertilization plans.