Lebanon Crop Management Video

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29 March 2016

Keeping tabs on heat units assists on maximizing scouting times particulary for Alfalfa Weevil

Del Voight- Penn State Extension.
There is a tremendous amount of time and effort put into determining key times for insect activity and determining soil temperatures and other weather related factors that dictate agriculture and crop growth activities.  One source of this information is the Pa PIPE modeling system.  If one were to navigate to this web site a screen shot would appear with various colorations to indicate the activity of either soil temperature, accumulated growing degree days and or pest and crop stage of growth.  Right now Penn State has dozens of locations with traps out to monitor for the Eastern Black Cutworm which is utilized to determine a peak flight date and then that information is fed into the PAPIPE for growers and scouts to refer to estimate the peak cutting time for this pest in corn.

  Below is an example of the screen shot of the activity of flea beetle based on the heat development and know activity of the pest.   From this one could derive that at the date of this writing the flea beetle in the area of Lancaster is now in the larvae to pupa form and will be transforming into the adult. One will note that there are numerous tabs on the right hand column that allow one to toggle between heat unit, soil temperature and other known pests.














Here is another screen shot detailing soil temperatures as of today.  One can easily determine that much of the state currently is below 50 degrees in soil temperature and it clearly outlines the climatic differences that exist within Pennsylvania.
 One key area that crop managers utilize is growing degree days.  There are different thresholds of temperature used to determine the heat development each day.  For the most part 50 degrees is the base however there are acceptions like alfalfa weevil which is a base of 48 and corn rootworms which is a base of 53.  Here is a map of base 50 development. The pest tabs on the side of the column would be expected activity by different pests based on research completed on their specific development.  If one assesses this map as of today there are less than 250 heat units to date.  However this is base 50.


There are numerous articles that could be derived from a discussion of heat and the development of pests. For this week the one insect that should be tracked are alfalfa weevils as an example of the use of these models. Judging by the accumulated heat with a base of 50 with right around 250 or less as of today I double checked with my records that I keep in the Lebanon office and at this point there are 170 heat units that apply to weevils this is based at 48 degree growth . I inspected a few fields in the Lebanon area and found some signs of the larvae with shot holes on south facing slopes and very small larvae so if we get some significant heat in the next week damage will be more evident. Years ago with Paul Craig  we began to notice that when alfalfa weevil damage was clearly evident the colts foot and the Bradford Pears were blooming this is called a phenotypic indicator and if it holds true this year the Bradford Pears are just beginning to bloom so it is working out with our heat unit models that the weevils are becoming active. We have not seen economic levels of this pest but it is one to keep tabs on each year. As we develop more heat the weevils will grow and develop and while typically held in check by disease and other predators they could develop.

When should scouting begin?

Larvae begin hatching at approximately 200 degree days in fields south of I-80, and 250 degree days in fields north of this highway. Typically in Pennsylvania this accumulation occurs early in the month of April. Time scouting from 3-500 heat units. This sometimes correlates to just before alfalfa enters the bud stage or around 640 heat units(base 41), however in explosion years we have seen this much earlier.

Where should you start scouting?

Begin on south-facing hillsides. Larvae will hatch here first because these areas warm up quicker than northern hillsides.

How do you scout for alfalfa weevil larvae?

Save some time by using a sweep net to quickly and easily determine if larvae have hatched in your field. If larvae are found in the net, then collect 30 stems and look for larvae in the upper leaves. When collecting stems, do not break them too hard or you will knock off larvae still on the plant. The best way to collect the most larvae is to grab the tip of the plant with one hand and break the base of the stem with the other hand, or cut it with a knife. Place stems inside a white, 5-gallon bucket and beat them against the side. Large larvae will dislodge and can be counted easily, but newly developing leaves must be pulled apart to find very small, newly hatched larvae hidden in the plant tip.

What do alfalfa weevil larvae look like?

They have a very dark head, almost black, and are pale green with a white stripe down the back. They are about 1/16 of an inch in length when they hatch and may be light yellow. After feeding for several days, they turn green. They are 5/16 inch in length when full grown.
Alfalfa weevil are small; less than 5/16-inch long.


Are there any other insects that look like alfalfa weevil larvae?

Yes. Larvae of the clover leaf weevil look very similar, but are larger, have a light brown head, and often have the white stripe edged with pink. Clover leaf weevil larvae usually hide around the base of the plant during the day and feed mostly in lower leaves at night. They rarely cause economic yield losses and should not be counted as part of the alfalfa weevil sample.

When should alfalfa weevils be controlled?

If two or more larvae are found per stem, and 40 percent of the stems show any leaf feeding, the best option is to cut the hay within 5 days, if possible. This method of cultural control avoids the use of insecticides. If the crop is not mature enough to cut, then chemical control may be an option, depending on the economic thresholds.

What are the economic thresholds for chemical control?

New economic thresholds have been developed by University of Nebraska entomologists. These thresholds are for alfalfa at the early bud stage, when third- and fourth-stage larvae do 90 percent of the damage. To use the economic threshold chart, first determine the control costs in dollars per acre, then estimate the forage value in dollars per ton. Where these two values intersect (Table 1) is the average number of alfalfa weevil larvae per stem needed to justify chemical control. For example, if control cost is $10 per acre and forage value is $75 dollars per ton, then an average of 3.4 larvae per stem would be needed to justify chemical management (Table 1).
 Table 1. Economic thresholds for alfalfa weevil larvae in early bud stage alfalfa (average number of larvae per stem). Current high prices of forages will impact this chart.  Entomologists will need to adjust to this current market pricing. For now here is a relative economic chart.

Forage value ($ per ton)
Control cost

($ per acre)
45
55
65
75
85
95
105
115
7
4.0
3.3
2.8
2.4
2.2
1.9
1.8
1.6
8
4.6
3.6
3.2
2.7
2.4
2.2
2.0
1.8
9
5.2
4.2
3.6
3.1
2.7
2.5
2.2
2.0
10
5.8
4.7
4.0
3.4
3.0
2.7
2.5
2.2
11
6.3
5.2
4.4
3.8
3.4
3.0
2.7
2.5
12
6.9
5.6
4.8
4.2
3.7
3.3
3.0
2.7
13
7.4
6.1
5.2
4.5
3.9
3.5
3.2
2.9

Resample the field in 3 to 5 days. Chemical management may be needed then, or possibly the crop may have reached a stage where it can be cut.

What if the weevil count is below the economic threshold?

Several days after it would be important to recheck to determine if thresholds are reached otherwise there is a point of no action.

What chemicals are labeled for alfalfa weevils?

Several chemicals that can be used for alfalfa weevil control are shown in Table 2. Read and follow all label directions before using any insecticide. The Agronomy Guide has more specifics.
Table 2. Insecticides labeled for alfalfa weevil.

Insecticide
Rate per acre

at low and high rates
Harvest

interval

(days)
Cost/Acre Jan 2014 Pricing. At low and high rate.
Ambush 2E
6.4-12.8 ounces
0-14
2.94-5.87
Baythroid XL
1.6 - 2.8 ounces
7
1.68-4.71
cylfuthrin 
various

cyhalotharin
various

Lorsban 4E
1-2 pints
14-21
3.34-6.68
gamachalothrin
various

Pounce 3.2EC
4-8 ounces
0-14
1.84-3.67
Sevin XLR+
3 pints
7
9.56
Warrior 1T/Proaxis
2.56-3.84 ounces
7
3.78-4.34
Mustang Max
2.24 to 4.0 ounces
3
????
Cobalt
19-38 ounce
7-14
6.67-13.35

28 March 2016

Cereal Rust Mite, Abacarus hystrix(Nalepa): A pest on Timothy

Introduction:
The presence of this mite as a significant factor of timothy losses has been reported in Lancaster, Lebanon, Dauphin and York counties over the past 2 years.  Some yield loss estimates range from 30-70% loss of yield.  This problem, however, has most likely been present for a longer period of time but gone unnoticed.  In Maryland, problems have been seen for the last 10 years. When the problem first occurred in during the early 1990's in Maryland, the mites only infested the variety Climax, but high populations of the mite have recently been encountered on other varieties.  In 1999, the mite was officially identified as the cereal rust mite, A.  hystrix, by Dr. Ronald Ochoah, a USDA-ARS mite specialist.  This is the first record of this species in Pennsylvania.  A.  hystrix has been infesting timothy for some time, but due to its small size, growers have attributed its subtle injury symptoms to agronomic reasons.  Based on grower contacts and surveys by extension personnel in Maryland, Delaware, and Pennsylvania, the range of cereal rust mite infestations is expanding and virtually every acre of timothy grown in central and western Maryland and southeastern Pennsylvania is infested to some degree.
             Timothy hay is a very profitable cash crop produced on an estimated170,000 acres in Pennsylvania.  It is usually marketed to the horse industry at premium prices ranging from $75 to $180 per ton. Gross revenues for this crop range from $216 to $315 per acre.  The prices of good quality timothy hay can exceed that of alfalfa.  Production of timothy in Pennsylvania is currently not high enough to satisfy the horse industry; so considerable quantities of timothy are imported into the state to meet the demand.  Thus, reductions in the yield and quality of timothy grown in Pennsylvania result directly in economic losses  to growers and indirectly to horse owners who have to pay higher prices for imported hay.

Description:
Adult rust mites are very small (<1mm). They are spindle-shaped, with four legs and may be white, yellow or orange. You will need a hand lens to
see them. To check for eriophyid mites, look for off-color foliage, leaf or bud abnormalities. Use a 10X or 20X hand lens. Large mite populations often produce many elongate, white shed skins. The mites feed on bulliform cells at the base of grooves on the adaxial leaf surface.  Eggs are deposited in the grooves, and both eggs and immatures become distributed higher in the canopy as leaves unfold.  Adult mites move downward in the plant crown, where they prefer to feed on the youngest tissues of the plant.  The mite undergoes numerous generations per year (a generation time of 16-18 days at 20o C) and there is no known diapause stage.  Although development is reduced, mite stages are active during the winter in the crowns of its host plants.
Injury:
            The feeding of A. hystrix causes direct injury to timothy, which results in retarded growth, stunting, and discoloration.  No other pest species or agronomic factor is more important as a constraint in timothy production than the cereal rust mite.  The feeding of A. hystrix causes direct injury to timothy, which results in retarded growth, stunting, and discoloration. Severe mite infestations have two negative impacts on local growers.  Feeding injury causes substantial yield losses, as much as 50%, and also reduces hay quality by the brown discoloration.  Horse producers are reluctant to buy hay that is not the normal color of quality timothy.  As a side note, A. hystrix is also known to vector ryegrass mosaic virus (RMV), a serious disease of temperate grasslands, and may be a vector of agronpyron mosaic virus (AMV), a minor disease of wheat and other grasses.  These diseases cause substantial losses to pasture production in other parts of the world, especially in Europe.  However, the presence of RMV and AMV in the USA has not been detected.  The symptoms of feeding injury on timothy resemble the typical symptoms of a viral infection; however, disease infections have never been confirmed by ELISA determinations.  Nonetheless, if these foriegn viruses enter the US, there exists the potential for their virulence on forage grasses and wheat due to the abundance and wide distribution of the mite vector.  
Time of Attack:
            Adults and eggs are present overwinter and the adult hatch begins in March with the peak adult population peaking in April.  Damage is most evident in April and will continue into May.
Scouting:
            Growers should observe fields in early to mid March and look for the presence of small round eggs in the grooves of the timothy leaf surface. 
Economic Threshold:Lebanon Timothy mite Experiment(Field research and Demonstration)
  

Treatment is recommended in fields with a previous history of cereal rust mites and/or when 25% of the plant tillers exhibit curled tips of the new leaf blades within several weeks following green-up.  There are no know thresholds developed to date.  Research is underway to develop a monitoring plan and threshold levels for economic justification of treatment.  The following tables provide some economic analysis of the pest.
Video for Scouting.
Scouting Rust mites on Timothy

22 March 2016

Powdery Mildew on Wheat What product to choose???

If you follow the chart there are some inexpensive alternatives that provide ideal management of Powdery Mildew.  The key differences seem to be in the control of rust.  Older triazoles in general seem to do very good on the PM while lacking in the rust area. The strobularins and newer triazoles seem to be reliable for rust management.

Del Voight
Senior Extension Agent - Penn State Extension

Plant Tissue Testing Winter Wheat to determine fertility needs this spring


Del Voight- Penn State Extension

Several growers are considering more high yield management for the wheat crop. A few growers last season enjoyed 100 bu/acre plus while managing for high yield wheat crops.  The first step is to gain an accurate soil test. The second step is to collect a sample in the spring for plant analysis. The Ag Analytical Lab provides the testing for the results.  Here are the specifics to gather the samples.
Once the plant fully greens up when the weather breaks gather the samples and send them off. This will allow for adequate time to determine a nutrient strategy before peak growth at GS5 Wheat Growth Stage Diagram.

Small grains
Seedling stage (less than 12”...All the above ground 50-100 plants)

or
Prior to heading The 4 uppermost leaves. 40-50
Sampling after heading not recommended
Once you get the results refer to this site for more specific information on the what is acceptable levels in the plant.
Key nutrient numbers for wheat


Freezing injury impact on Wheat?

Del Voight - Senior Extension Educator Penn State Extension
Recent cold weather may create questions as to what impact if any the freezing temperatures have on wheat.  As one can see based on this table that appeared in the Kentucky Decision Guide for Wheat.  Growers that perhaps planted early and have wheat that is approaching jointing they might experience more of an affect than the wheat that I am seeing in my area that is still tillering at this time. For more reading follow this link to the original document.  http://www.ca.uky.edu/agc/pubs/id/id125/03.pdf

Assessing Alfalfa Stands

Dr. Dan Undersanders how to assess alfalfa stands now.

How to assess spring Stands of Alfalfa

Key Numbers to assess right now.
Factsheet to bring to the field during assessment.

Marvin Hall, Forage Specialist

Unfortunately, “taking out” or saving and alfalfa stand is not always an easy decision. But with the current price of corn I think that decision will be on the minds of many Pennsylvania farmers. Recent research can help in assessing the productivity and profitability of a questionable alfalfa stand.
The magic number of plants, that traditionally indicated when it was time to rotate out of alfalfa, has been 4–5 plants per square foot. However, depending on fertility and weed invasion, alfalfa stands with 5 plants per square foot can yield as much as a stand with 10 or 15 plants per square foot. The correlation between plants per square foot and yield is very low since individual alfalfa plants respond to decreasing stand density by producing more stems. An increase in stems per plant compensates for fewer plants and maintains the yield.
A better indicator, than the number of plants, of the productivity of an alfalfa stand is the number of stems per square foot. Fields with 55 or more stem per square foot produce maximum yields. As the stem number declines below 55 per square foot yields begin to decline. Once stem numbers falls below 40 per square foot alfalfa fields begin to loose profitability and should be rotated out of alfalfa.

21 March 2016

Wheat Management Considerations in SE Pa.

Del Voight- Penn State Extension
Currently there are some fields that are entering GS 6 in wheat today in fact it is possible we had some wheat going into this phase prior to freeze out in December. You will note some key principles in identifying the stages. If you feel the stem at the base and slide your finger up the stem you will note a joint that is enlarged this is the first inter node. Once this is formed the GS stage 6 is formed. There are some key things to be looking for at this stage. The low hanging fruit is controlling weeds. For most products you have until GS 7 to make this application. Not sure what weeds you have in the field?  I find the Early Spring weeds of No till the best reference for this time of year. Here is a copy. Early Spring Weeds of No Till  If the wheat is this far along one might be considering additional nitrogen for it is at this stage that peak uptake of N occurs during this GS 6 and GS9 stage(source AG DWEEB)
 Also inspect plants for powdery mildew
as this field condition might lead to further infection and a fungicide may be warranted at this stage PARTICULARLY on varieties that are not tolerant of the disease. If you decide to apply a fungicide utilize the included reference to determine the most economical product and ensure it has activity on both Septoria and Powdery Mildew.  Dry weather can halt powdery mildew growth and typically wet weather brings on the Septoria disease so consider the forecast as well.   The addition of Palisade EC (it does have a WARNING label so protect your eyes and wear proper safety equipment) a recent growth regulator might be beneficial as well to prevent excessive growth and the ideal timing for this application once in GS 6 is in play. Here is the label discussion on timing.  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 fi rst application at Feekes 4-6 and a second application at Feekes 7-8. Use the higher rate when 1) varieties are prone to lodging, or 2) the crop is intensively managed.
So there is alot to consider once the plant enters this growth period. We have numerous references to assist in any of these decisions in the Agronomy Guide.



 Here is a picture of the developing head of wheat indicating GS6. This is critical stage and an assessment of the recent freezing temperatures will require an inspection of this head to ensure it has not been affected by low temperatures.
Finally, Wisconsin Extension has this handy guide similar to our Penn State Guide but in color and includes a little timing detail for key pests.

15 March 2016

Double Crop Soybean Population results

Del Voight- Penn State Extension
Here with are the results from an initial ongoing trial looking at the relative impact of planting rate performance under a double crop soybean scenario.  Plantings varied from 140,000 up to 230,000 ppa there appears to be a response between 140 and 170,000ppa but not between 170 and 230ppa. As we move into conducting more trials this coming season the goal is the increase the profitability of double crop soybeans.


Double Crop Soybeans Seeding Rate by Variety, 2015
Seeding Rate
Maturity Group
Yield,
bu/A
Height (in)
Lodging (0 - 5, 0 = Best)
Test Weight
Final Stand
% Protein
% Oil
Seeds per lb
140,000
AG3735
37.2
22
0
56.5
167,283
37.2
16.0
3,682
140,000
TA 3759
40.2
24
0
56.1
184,985
38.2
15.7
3,296
140,000
Mycogen 388NR2
39.0
23
0
56.4
146,926
37.1
15.3
3,685

Mean
38.8
23
0
56.3
166,398
37.5
15.7
3,554
170,000
AG3735
42.5
25
0
56.1
180,560
37.5
16.0
3,369
170,000
TA 3759
47.3
25
0
56.0
197,376
38.2
15.5
3,389
170,000
Mycogen 388NR2
40.0
27
0
55.3
185,870
37.0
15.9
3,426

Mean
43.3
26
0
55.8
187,935
37.6
15.8
3,395
200,000
AG3735
48.4
25
0
56.1
245,172
36.7
16.9
2,996
200,000
TA 3759
47.7
26
0
55.5
198,262
38.2
15.5
3,582
200,000
Mycogen 388NR2
40.3
26
0
55.7
183,215
37.1
15.5
3,381

Mean
45.5
26
0
55.8
208,883
37.3
16.0
3,320
230,000
AG3735
43.8
24
0
55.9
238,091
36.9
16.4
3,128
230,000
TA 3759
51.7
25
0
56.3
270,839
38.6
15.4
3,435
230,000
Mycogen 388NR2
50.8
29
1
55.6
229,240
38.0
15.1
3,401
Mean
48.8
26
0
55.9
246,057
37.8
15.6
3,321
Mean

44.1
25
0
55.90
202318.2
37.6
15.8
3,398
LSD Seeding Rate (.05)
4.9
-

LSD Variety (.05)
NS (p-value = .1013)
-

LSD Interaction (.05)
NS (p-value = .2665)
35,706

LSD Seeding Rate (.25)
2.8
-

LSD Variety (.25)
2.5
-

LSD Interaction (.25)
NS (p-value = .2665)
20,715

CV %

16.6



15.3





*********************************************************
Greg W. Roth
Professor of Agronomy
Penn State Extension
Department of Plant Science
Penn State University
116 ASI Building
University Park, PA 16802

Phone: 814-863-1018
Email: gwr@psu.edu
Web: extension.psu.edu
 
Website: 
http://cornandsoybeans.psu.edu
*********************************************************