Defoliation Options

We got extremely hot and dry the last few weeks of the growing season which pretty much shut down our dryland cotton production.  The conditions caused much of the top crop to be stunted and very poorly developed.  It also shut down terminal growth which would have been good for defoliation and boll opening.

However, we were not that lucky.  A few recent rains and slightly milder temperatures caused most of our cotton to resume growth.  Now we have fields across the region that look like the picture below.

Not only do we have to try and open bolls and defoliate the crop, but now we have to control the young tender shoots that are present.  Every field will be a little different than the next but most of the ones that I have been in would benefit from a 3-way mixture.  Something for boll opening plus defoliation and regrowth control.

We don't want to spend any more money than we have to but we also don't want to make a mess and have to put the sprayer back into the field a second time.  let's say that the 3-way mixture of thidiazuron + diuron + ethephon costs you $12.00 per acre.  What would happen if you wanted to save $2 -3 dollars by leaving out the thidiazuron?  Most likely the young tender regrowth in the field would not be removed and you would need to retreat.  Instead of saving $3 you end up spending more than $5, plus the time to spray and the delay in harvest.

Like I said in the beginning every field and every situation is different but in most cases I feel that the 3 way mixture of boll opener + defoliant + regrowth control is going to be needed this year.

Early September is Critical for Pecans

This information was taken from Dr. Lenny Wells' Pecan Blog

The nut sizing period normally occurs from May 1 through August 15. Although not a critical water use stage for pecan, serious drought conditions during this period can affect yield. The most common visible effects of an extended drought during this period are excessive nut drop and “shell hardening” on small nuts. Lack of sufficient water during the nut sizing period causes small nuts and may lead to water stage fruit split, resulting from a sudden influx of water during the nut filling stage in some varieties.

The nut filling stage occurs from about August 15 to the first week of October, depending on variety. The most critical period for water use is during the first two weeks of September. Lack of sufficient water during the nut filling stage will lead to poorly filled nuts, which will result in poor nut quality.

Reports from other areas of the country indicate that as much as 350 gallons of water per day can be required by each tree during the nut filling stage. Based on this recommendation, if a mature orchard has a plant density of 12 trees per acre (60' x 60' spacing), then 4,200 gallons per acre per day may be needed. For a density of 20 trees per acre (46.5' x 46.5'), 7,000 gallons per acre per day may be needed.

Pecans can have high water requirements, using as much as 60 inches of total water (including rainfall) during the growing season. Drip and micro-irrigation system design capacity for a mature pecan orchard should be 3,600-6,000 gallons of water per acre per day.

New Sorghum Pest

The sugarcane aphid has been around for a while.  It was first observed in Florida on sugarcane in 1977.  Then in 1999 it was discovered in Louisiana on sugarcane.  It was not until 2013 that it was found in Texas and this time it was found on sorghum. 

Since this discovery it has been found as far east as Alabama and it now looks like it has made it into western Georgia.  Roger Sinyard and Bill Starr responded to a call from a local grower who was seeing something weird in his field.  It is somewhat ironic that we visited a field day in Plains GA, earlier in the week and learned about this new and emerging pest of sorghum. 

When David Buntin (UGA Entomologist) spoke about it I remember thinking that we should have a couple of years before we see it here.  Well, I was wrong.  This aphid can be seriously damaging in more ways than one.  Early infestations can kill or stunt small sorghum.  Late infestations can result in large amounts of honeydew.  This excessive stickiness can interfere with harvesting.

It is unofficial until our entomologist examine the samples sent last week, but we are pretty sure that we are seeing the sugarcane aphid in our area.  to learn more you can visit this site
http://www.amsac.org.mx/docs/PUB0272_SugarcaneAphidPublication.pdf

Disease Resistance

In a year like this you expect to see plenty of Pecan Scab on trees that have not been sprayed.  Pecan scab is always worse in years when we have ample rainfall in early spring.  That is exaclty what we saw this year and last as well.  However if trees are taken care of and the proper fungicides are applied we should be able to control this devastating disease.

Pictures came from Patrick Connors (UGA Pecan Breeder) website

So why are we seeing so much scab in treated orchards?  It could be due to diseases becoming resistant to certain fungicides.  We are not seeing complete resistance like we see with resistant pigweed, but we are seeing a shift in sensitivity to certain fungicides. 

Several local growers have participated in a program offered by UGA.  They have been submitting samples of scab from orchards across their farms and the results are pretty interesting.  Across many of the test sites there was at least some level of insensitivity to several of the fungicides.  

There was low to moderate insesitivity to the triazole fungicides like propiconazole and tebuconazole.  There was low to high insensitivity to strobilurin fungicides like azoxystrobin, and TPTH (Tin).  In the samples submitted there was little to no insensitivity to Dodine and Thiophanate Methyl.

This does not mean that we have widespread disease resistance.  It does make me want to recommend growers submit disease samples for analysis.  If we can find insensitive scab then we can change our spray program to better control the disease.  The only thing that it will cost you is postage and the time it takes to get the sample.

You can get instructions for collecting and submitting samples at the following link
http://www.caes.uga.edu/commodities/fruits/pecan/documents/PecanScabSamplingInstructions-REVISED.pdf

Spray System Cleaning

The basic cleaning methods for agricultural sprayers is to empty the tank on the approved crop.  Fill the tank 10% with water and flush the lines.  If you plan to add a tank cleaner you should do that on the second rinsing.  Fill the tank mostly full on this rinse, and flush the system.  For the third step repeat the initial rinse.

I bring this up because of something I learned at a meeting yesterday.  Dow AgroSciences had a field day to introduce some new technology.  One of the stations talked about sprayer clean out and its improtance.

John Deere conducted a study on a sprayer with a 100 foot boom and 1000 gallon tank.  After spraying the tank out they took the sprayer back to the shop and drained all of the liquid.  So what they collected was water that was in the pumps, low hanging lines, filters, etc.  They collected this water multiple times and ended up with between 50 and 100 gallons of water still in the system. 

So if you were spraying 15 gallons of water per acre you would have enough spray left in the lines to treat almost 7 acres.  This is very important if moving sprayers between highly sensitive crops. and will be very important as we move to new weed resistant crops in the near future.