The snow storm on April 12^th led to the one of the latest potato plantings in Central Wisconsin in recent memory. Weather since has been seasonable which allowed growers to catch up with planting schedules and led to crop emergence by early to mid-May in Central Wisconsin. A slight freeze on May 16 to 18^th did little damage to potatoes. Most of the crop has been hilled and side dress fertilizer applications are underway.

 

Dry conditions across Northern Wisconsin allowed for efficient planting of potatoes in Langlade County.  In addition, planting has begun across many of the muck farms in the state. The crop had not emerged by last Thursday following planting on on muck and at Antigo by May 10^th.  

 

Crop stands appear to be good to excellent as indicated by Walt Stevenson later in the newsletter. The crop emerged quickly decreasing the potential for damage to emerging sprouts. In addition, good soil moisture resulting from the snow and delayed planting resulting in longer conditioning of seed may have prevented seed piece decay. I have seen one plant with dark lesions on the stems in research plots, but few others showed any sign of stress during emergence.

 

The crop development has progressed in Central Wisconsin, with the canopy 25% closed in some varieties.  Tubers had initiated on some round white and red varieties by Wednesday last week with the stolon tips showing enlargement. Other varieties, such as Russet Burbank, had just started forming stolons and there was no indication of tuber initiation, but that may have changed since last Thursday. Later emerging potato varieties such as Bannock Russet, had not formed stolons as of last week.

 

Tuber initiation is key time for crop development and beginning of the potato crops sensitivity to drought stress. Drought stress can lead to decreased cell division in newly forming tubers resulting in decrease in potential tuber size. In addition, drought stress during tuber initiation and during early bulking can lead to sugar end and limit solid content of harvested tubers. 

 

The lack of rain has required growers to initiate irrigation on potato fields that have only limited canopy development. Relative ET rates for much of the potato growing areas have averaged nearly 0.2” per day. Soil moisture should be monitored closely during tuber initiation and early bulking to limit effects of drought stress on crop yield and quality.

 

Fortunately, soil temperatures have only reached 75 to 80 F on sand soils in part due to cool night temperatures.  Open canopies with clear skies can lead to warm soils. Darker and heavier silt loam soils in Southern Wisconsin have reached soil temperatures of over 100 F over the past week. 

 

Automatic e-mails will again be sent daily with ET and cumulative P-days. Growers can register for the e-mail service by entering the latitude and longitude of your farm or various fields at UW climatology website http://www.soils.wisc.edu/wimnext/water.html .