Monthly Archives: May 2019

Pecan Water Requirements and Heat

We have some very high temperatures in the forecast for the next several days. With this in mind, I wanted to provide some irrigation suggestions. The irrigation schedule below is the recommended schedule for drip and microsprinkler on pecan in Georgia. As you can see you should move up to 35-40% of the maximum amount in June. It is probably a good idea to go ahead and move to that June rate at this point with the high temps and the onset of nut sizing coming up. With temperatures up around 100 degrees for several days growers will be tempted to increase the irrigation further. However, this is not necessary. Pecans are adapted to heat, and in fact, need it. Photosynthesis begins to shut down in many plants once temps get above 94 degrees. Pecan, however, can still function normally at temps of 106 degrees as long as they have the water they need. The June rate of 35-40% of maximum is adequate for mature pecan trees on drip or micro-sprinkler at this time. For solid set systems you should be at 1″ per week.

For non-bearing trees, I would go up to as much as 170 gallons/week during the heat wave and dry weather on sandy soils.

 

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Peanut Weed Control Update for May 23 (Prostko)

A few things to think about in regards to peanut weed control given the current weather conditions:

1)  Rainfall events on Mother’s Day Weekend (May 9-13) caused some Valor related peanut problems in many areas of south Georgia (Figure 1).  Since I have addressed this issue numerous times in other blogs, I feel no need to bloviate any further.  But, this problem should not be a surprise to anyone who has ever used Valor in the past.  Valor injury will almost always happen when rainfall events occur from cracking up until about 2-3 weeks later.  Historically, this injury has been cosmetic only and not resulted in reduced peanut yields.

Figure 1.  Valor injury at UGA Ponder Farm, May 14, 2019.

2) Cracking/EPOST applications of paraquat mixtures or solo applied Storm or Ultra Blazer should be delayed as late as possible in peanut fields suffering from Valor injury.  I would argue that if Valor injury has occurred, then good weed control has also occurred and a cracking treatment might not really be needed.  Paraquat treatments can safely be applied in peanuts up to 28 days after cracking.

3) Common paraquat mixtures include paraquat + Storm or Basagran + Dual Magnum or Warrant or Zidua.   I have no preference between Dual Magnum, Warrant or Zidua.   There is no need for additional adjuvants with Dual Magnum mixes but a NIS (0.25% v/v) should be used in Warrant or Zidua + paraquat tank-mixes.  FYI, I am not a huge fan of paraquat + Dual Magnum or Warrant or Zidua without any Basagran/Storm due to greater injury potential that might reduce yields (especially under these lava-like weather conditions). Also, paraquat without Basagran/Storm is not very effective on smallflower mg (Figure 2).

Figure 2.  Smallflower morninglory

3) With paraquat mixes, I prefer Storm (bentazon + acifluorfen) over Basagran (bentazon) due to the variety of weeds that can occur in any given peanut field in Georgia.  My typical recommended use rate of Storm in EPOST paraquat tank-mixes is 16 oz/A.  If need be, growers can make their own “Georgia” Storm by mixing 16 oz/A of Ultra Blazer 2SL + 8 oz/A of Basagran 4SL (yesthis is a slightly hotter mix than 16 oz/A of Storm).

4) It is very hot and very dry right now.  Non-irrigated growers who were planning on using paraquat tank-mixes after peanut emergence might want to re-considering their options.  Why?  Rainfall/irrigation is critical in helping peanut plants recover from paraquat injury.  I do not think that irrigated growers need to worry about this issue since they can help the peanut plants recover from paraquat injury with well-timed irrigation events.

5) When paraquat + Storm/Basagran + Dual/Warrant/Zidua mixtures are applied in peanut, there is no need to be a great ID’er of weeds since these mixes control just about everything (small grasses and small broadleaf weeds).  But, if a non-irrigated grower decides to go with something other than paraquat mixtures (which is fine), such as Ultra Blazer or Strongarm or Cadre or 2,4-DB, they better know what is in the field since these herbicides are not as broad spectrum.  I am not comfortable with very early applications of Cobra unless the peanut plants have reached the 6 true leaf stage.

6) No matter what I say or do, if it don’t rain, it don’t matter! (That’s a famous quote from former UGA Extension Peanut Specialist, Dr. John Baldwin)

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