All posts by Dave Verbree, Crop Physiologist and Agronomist

weather.utcrops.com

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A new tool for tracking weather, heat units, and crop progress

I needed a quick way to view and download weather data from several counties, to determine accumulated heat units for many different planting dates and crops, and to compare against the 30-yr averages for making predictions and crop management decisions. So, I developed a web-based tool with that express purpose. Just point your browser or click-on http://weather.utcrops.com and the rest should be self-explanatory. There is also a Quick Link to this site on the left menu. If you are only interested in counties in Tennessee, you can click on Continue reading


Heat unit status in cotton

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Dave Verbree and Tyson Raper

As of 8/26/14, this cooler than normal year has set cotton back by 166-215 heat units depending on the planting date (Table 1). Based on the 30-yr average, we typically accumulate about 18.5 DD60s/day during this time of year which puts our cotton 9-12 days behind schedule. However, we have been accumulating about 23 DD60s/day over the past 5 days which is helping us catch up. Unfortunately, the number of DD60s per day normally begins to drop about 0.2 degrees each day at this time of year.

We need about 1625 DD60s to reach 1st open boll and some of those who planted timely, did not over-fertilize, and managed for earliness are already there. We need about 2200 DD60s to reach maturity so we hope the above average temperatures will stick around a few more weeks. Realistically, most of us should expect cool temperatures during defoliation and plan to use a two-pass approach, relying more on our herbicidal defoliants to finish off the job. We will post more about defoliation in the coming weeks.

Table 1. Accumulated heat units (DD60s) for Jackson, TN by planting date.

Planting date 2014 30-yr avg. Difference
May 1 1758 1924 166
May 8 1716 1884 168
May 15 1616 1831 215

Cotton fruit-shedding – who’s to blame

Fruit shed in cotton
Fruit shed in cotton

Fruit shedding can be caused by bugs, disease, nutrient deficiencies, or the environment (as affected by weather or management). Even in the absence of pests and on fields with good fertility, it is common for a cotton plant to shed 60% of its squares and young bolls under typical growing conditions. Although fruit shed normally increases dramatically as the crop approaches cut-out, it can occur anytime and even with relatively small changes in the weather. What causes fruit shed and is there anything we can do to prevent it? Continue reading