Month: April 2020

Risk of Freeze Damage to Winter Grains

Del Voight – Penn State Extension

Winter small grains are at risk of damage by low temperatures. We experienced two rather short duration cold temperature events last week. In as little as 2 hours of a freeze below 30 the result could  impact the crop yield of this 2020 crop depending on the stage of growth, soil type and residue cover. As it begins to form the head at jointing  stage it must be protected from weather, pests and nutrient deficiencies. Below is a  photo I took about a week after a 19 degree overnight temperature of some tip burn from some wheat in the jointing stage. This has little impact on yield.   It takes time to really assess these fields perhaps  even as long as 10 days after a cold temperature event to assess damage. Time will tell how deep the freeze occurred and the impact on the head.


 The above photos are from Dr Heidi Reed and illustrates  prominent tip damage.At this point the fields that I have reports from do not have any discolorations in the seed head. Here is a picture of what the plant is doing right now at jointing with the hollow stem and the small seed head forming above that point. Some fields are much more advanced and the head is pushing final leaves out before heading. The seed head can be assessed to determine if has discolored and is affected by low temperatures. Depending on the stage and duration of low temperatures that will determine final impact. Just above the knife point one can find the small seed head and it appears unaffected by low temperatures.

 

 

 I was involved in some cases where liquid nitrogen applications  burned the wheat below the head and this resulted in a complete loss in the fields that were burned by the liquid N. This would be similar to this situation if the freeze reaches and destroys the tender seed head inside. Dr Paul Esker had assessed damage at our Southeast Research Station and did not find significant damage in both Barley or Wheat. If the seed head is unaffected the stem below also can freeze and split so watch for that as well. Brittany Clark in Franklin reported growers had received significant damage to Barley that were in the GS Stage 10.1 or head emergence.  They estimated that more than 30% of the fields with heads erect are now desiccated and will be lost.  The key point is to get out and scout the wheat and barley to inspect later this week and make an assessment as to the overall impact. If perhaps only low lying areas are affected this might not require a rotation to a different crop and or harvest as forage but rather a loss in those areas. Also there may be growth affects as the heads emerge.  This image is the failure of the head to fully emerge due to low temperatures earlier in the spring.

Another issue that may get many agronomists confused is if the stem or head inside the stem is damaged a purple coloring of the remaining leaves can mislead a diagnosis to phosphorus deficiency.  Check the stem and head to ensure no damage is evident. Dr Chad Lee in Kentucky has a informative fact sheet detailing wheat and freeze damage.  The table below is an excerpt from his writings and it provides the temperature and hours to become an issue.  Freeze damage affect on Wheat.(Kentucky Extension)

Table 3-3. Freeze injury in wheat.*

Growth stage

Feekes

Zadoks

Approximate injurious temp. (2 hrs)

Primary symptoms

Yield effect

Tillering**

1-5

20-29

12°F

Leaf chlorosis; burning of leaf tips; silage odor; blue cast to fields

Slight to moderate

Jointing

(6-7)

31-32

24°F

Death of growing point; leaf yellowing or burning; lesions, splitting, or bending of lower stem; odor

Moderate to severe

Boot

10

41-49

28°F

Floret sterility; spike trapped in boot; damage to lower stem; leaf discoloration; odor

Moderate to severe

Heading

10.1-.5

50-58

30°F

Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration

Severe

Flowering

10.51-.54

60-71

30°F

Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration

Severe

Milk

11.1

75

28°F

White awns or white spikes; damage to lower stems; leaf discoloration; shrunken roughened or discolored kernels

Moderate to severe

Dough (11.2)

11.2

85

28°F

Shriveled discolored kernels; poor germination

Slight to moderate

*Information in this table assumes timely rainfall events occurring after the freeze event.

Frost can also impact other crops as well.  The tips of alfalfa might get frosted off but the most severe impact will be  to small grains that are now for the large part in the jointing stage or in some early planted wheat at boot stage.
So the action is to wait and see what the plant tells you in the next week to determine if the freeze impacted the head development. Here is another informative factsheet that might prove useful as we begin to assess fields.  Cultural Impacts in wheat

In the end, time will tell how much these cool conditions has affected the small grain crop. As always reach out to an agronomist if you have any questions on how to assess your field situations.

Wheat Disease and Head Scab

Del Voight – Penn State Extension

There seems to be reports of Powdery Mildew on wheat that is susceptible all the resistance varieties seem to have little to no levels of Powdery Mildew. I have yet to view a field that I would spray. Now we need to time and watch the scab forecast. Here it is keep checking it to manage scab risk.

National Scab Forecast Tool

Also Miravis, Prosaro – 8.2 ounce/acre or Caramba at 9 ounces/acre would be the two products of choice as heads emerge.

Cereal Leaf Beetle activity

Del Voight- Penn State Extension

Checking on the PAPIPE interactive website.  I noticed that cereal leaf beetle activity is occuring with the hatch being slightly earlier than previous years.

This is a typical impact of feeding I run into frequently in some areas of Pa. The adults are out right now with reports to our south of activity. These adults will lay eggs and the picture below shows what I expect in the next couple of weeks.  Check fields weekly for the sign of the pest if noted at thresholds consider managing the pest.

OLYMPUS DIGITAL CAMERA

Here is the link to the management of this pest. As always please manage through the thresholds to ensure proper use of a pesticide.

https://ento.psu.edu/extension/factsheets/cereal-leaf-beetle

 

 

Using Growth Regulator on Small Grains(Cerone/ Palisade)

Del Voight – Penn State Extension
There are really two choices for wheat and barley to manage the potential for lodging. The key here is to know your variety. If it is prone to lodging one may then need to manage this potential with a PGR. If lower N rates and the variety is not prone to lodging then this is not needed to manage.  Another key is to know  the growth stages. Does it work? Yes if applied at the correct rate and timing. Expect about a 2 inch or so shortening the internodes from some of the research I have seen in the field. I have highlighted this for each product and I have included the following link as a refresher to understand the different stages of wheat.
Palisade Specifics(From Label)(PPE WARNING)
Rate of application – 10.5 – 14.4 0unce per acre
Single application:
Apply Palisade EC from Feekes growth stage 4 (pseudostem erection) through Feekes growth stage 7 (node formation). Apply before Feekes 8
(when the last leaf is visible).
Split application: Make the first application at Feekes 4-5 and a second application at Feekes 7. Apply no more than 14.4 fl oz/A total.
Split application in barley: Make the first application at Feekes 4-6 and a second application at Feekes 7-8.
For further descriptions of Feekes (and Zadoks) growth stages, see table at end of label.
Use the higher rate when 1) varieties are prone to lodging, or 2) the crop is intensively managed.
Application:
For best coverage and uptake, use a minimum of 10 gallons of water/acre. Palisade EC may be mixed
in a spray solution containing up to 50% liquid nitrogen fertilizer.
Specific Use Restrictions:
1) Do not apply if crop is stressed by drought, disease, or temperatures.
2) Do not apply more than 14.4 fl
oz (0.11 lb ai) Palisade EC/A/year.
3) Palisade EC may be applied until 45 days prior to harvest (45-day PHI).
CERONE brand Ethephon Plant Regulator  (PPE Danger) Specifics
Do not use CERONE as a tank mixture with insecticides or fungicides on crops stressed by adverse weather conditions, referenced above, or by insect or disease damage.
Crop injury or yield loss may result with tank mix application under stress conditions. (i.e., moisture, heat, cold, insect, disease).
CERONE + Tilt® tank mix application by air made under stress conditions may result in flag leaf burn and yield loss.
Do not tank mix with herbicides or nitrogen solutions.
Do not add adjuvants, surfactants, or wetting agents to CERONE brand Ethephon Plant Regulator.
APPLICATION TIMING
Apply when the flag leaf is just visible to boot stage, but before the awns have emerged or the sheath has split (Feekes—Large Scale
8–10, Zadok’s Code 37–45). Do not allow spray solution to contact exposed heads, as damage and reduced yield may result. Inspect
fields carefully to determine that application can be made at the proper stage.
APPLICATION
For CERONE brand Ethephon Plant Regulator to be effective, temperature after application should be at least 60°F.
Avoid spray overlap which can result in excess rate and yield loss.
Ground: Use a minimum of 7 gallons of water per acre when applied by conventional ground equipment. Flat fan nozzles are
recommended. Use a minimum of 5 gallons of water per acre with controlled droplet application (CDA) or air foil type equipment. To
prevent uneven application, adjust spray boom to plant canopy height and operate at moderate speed.
Air: Use a minimum of 3 gallons of water per acre.
USE RATES
Lodging pressure and environmental conditions will affect the CERONE brand Ethephon Plant Regulator rate needed.
On more responsive varieties, use only the 0.5 pint per acre rate. Consult your State extension specialist or Bayer CropScience
representative for more information.