Crop and Pest Report May 20, 2021

The May 20 to May 26, 2021 Weather Summary and Outlook

Last week in my Crop and Pest Report I mentioned we would likely record a warm week with spotty precipitation.  Looking at Figure 1, the spotty precipitation ended up being an appropriate term.  There were clearly pockets with some good rains, yet most of the region recorded little or no rain during the past week. 

Figure 1.   7 Day (168 hours) Rain Totals at NDAWN station through 10:30 AM, Wednesday, May 19, 2021

Almost the entire North Dakota Agricultural Weather Network (NDAWN) recorded above average temperatures in the period from May 12 through May 18.  Some parts of the northern Red River Valley were 8 to 10 degrees above average (Figure 2).  This next week will probably be a bit cooler, especially across northern North Dakota, but those cooler temperatures will be associated with cloud cover and rainfall, which will be very welcomed.

Figure 2.  Departure from Average temperature at selected NDAWN weather stations for the period of May 12 through May 18, 2021.

Most of you have likely heard that there are rain possibilities today (Thursday) through early next week.  This is the system I hinted to last week in this report.  I doubt any given spot will record precipitation each day, but there will be rain impacting at least a portion of North Dakota on each day through Monday.  There will likely be winners and losers as rain doesn’t fall evenly and there will very likely be locations that won’t get as much as they would like.  Yet, having said that, this looks to be the most widespread rain in a very long time.  Plus, the rains will come over several days, so if you don’t get much today, there will be other opportunities.  After this stretch of rain chances, I would not be surprised if another system impacts us toward the end of next week as this temporary pattern change looks to be lasting for 7 to 10 days.

The projected growing degree days (GDDs) base 50°, 44° and 32° for the period of May 20 through May 26, 2021 can be found in Figure 3.

Figure 3.  Projected Growing Degree Days, Base 32°,44° and 50° for the period of May 20 to May 26, 2021

Using May 1 as a planting date, accumulated growing degree days for wheat (base temperature 32°) is given in Figure 4.   You can calculate wheat growing degree days based on your exact planting date(s) here:

Figure 4.  Accumulated Growing Degree Days for Wheat (Base 32°) since May 1, 2021

Using May 10 as a planting date, accumulated growing degree days for corn (base temperature 50°) is given in Figure 5.   You can calculate corn growing degree days based on your exact planting date(s) here:

Figure 5.  Accumulated Growing Degree Days for Corn (Base 50°) since May 10, 2021

Soybeans also use base 50° like corn, but NDAWN has a special tool for soybeans that, based on your planting date and cultivar, can estimate maturity dates based on average temperatures, as well as give you GDDs based on your planting date(s) you set.  That tool can be found here:

Daryl Ritchison