Important Corn Pest Information

This spring Penn State Extension in Franklin County set up a network of eight sites to monitor populations of black cutworm moths and true armyworm moths. One of these sites was in the St. Thomas area. This trap received significant flights of both black cutworm moths and armyworm moths. These numbers raise the risk of damage by these pests, please read the following statements for management considerations.

The most important step for you to take at this time is increase your level of observation and scouting in your corn fields. The distribution of these pests can be very spotty, so it is often the case that very few acres are infested and will need to be treated with insecticides. Specific information pertaining to scouting, economic thresholds and life cycles are important to understand and consider. Initial scouting for these pests involves moth trapping, which indicates a possibility of local populations of caterpillars developing. Unfortunately, higher local populations of moths does not always lead to damaging populations of caterpillar, but the correspondence is strong enough to warrant a warning of potential damage to growers in the vicinity..

Black cutworm moth:

Cutting behavior of black cutworm caterpillars is expected 300 growing degree days after the significant flight. The Penn State Agronomy program in Franklin County has recently established a weather station in Chambersburg Pa and has been tracking growing degree days since the significant flight occurred. The threshold was reached on Sunday 5/23/2010. Now is the time to start scouting corn fields to look for cutting damage. Economic thresholds for treatment are 2, 3, 5, and 7 cut plants per 100 for seedling, V2, V3, and V4 respectively.

Treatment options for at-risk areas vary but can include higher rates of neonicotinoid seed treatments where corn has not been planted and planting lines of Bt corn with activity against black cutworm if seed is still needed; however, growers should recognize that neither of these options are completely effective. The most economical control method for cutworm is scouting fields and applying rescue treatments where cutting activity exceeds economic thresholds.

More information on this pest can be found online at http://ento.psu.edu/extension/factsheets/black-cutworm , or by visiting the local extension office.

True armyworm moth:

One of the most important management considerations when dealing with true armyworm is to make sure in areas where you have cover crops or heavy weed cover that you allow a 2 week period after the plants are dead until you plant. This would lead producers trying to get a timely planting of corn who have yet to spray to use a quick killing herbicide such as gramoxone instead of glyphosate.

Once corn is established scout fields closely, especially where heavy cover was. If you find more than 10 percent of your corn in a given field has an infestation of armyworms treatment is encouraged. Armyworms typically are found hiding in the whorl of corn during the day and their feeding creates a ragged looking leaf. In bad cases the leaves will be fed on until nothing but the mid-rib is left.

More information on this pest can be found online at http://ento.psu.edu/extension/factsheets/armyworm, or by visiting the local extension office.

Finally, I would ask that you share this with other farmers in your area who may not receive Agronomy Notes. The greater the awareness of this issue, the less likely we will have economic losses due to these pests. As always, if you have any questions or need hard copies of the fact sheets mentioned above feel free to contact me at the extension office 717-263-9226 ext. 227. I am often away from my desk but check messages frequently.

IPM Update

As it seems moth numbers are starting to dwindle all over the state it is a good time to look back on what we have found this spring. As noted previously, St. Thomas was the only area that received significant numbers of true armyworm or cutworm moths. When looking at the graph above you can see the trap locations and the sporadic numbers throughout. Populations of both of these species are notoriously spotty. This year's network, I believe, has confirmed this once again.

Due to their sporadic nature it is very hard to know if and when you may have an issue on your own farm with these species. This unknown is why we typically rely on a pre-season application of insecticide as a little insurance policy against these pests. Two issues arise with this type of management. The first issue is that this certainly does not follow the IPM framework of spraying only when a pest population is present and at threshold levels. The second issue, which also has become apparent this year is the timing of the insecticide application may often be wrong for the pest. St. Thomas's significant flight happened on May 28^th. This means any insecticide applied more than a day or two before would have little to no affect on these pests. The moral of this means you are not limiting your damage simply by placing an insecticide up front with your burn down. If you had an insecticide placed on your fields prior to the significant flight you would still have to scout and possibly spray if thresholds were reached just like your neighbor who did not apply an insecticide.

Another question often raised with these pest centers around Bt corn and its control on these pests. Traited corn has become somewhat a norm in much of our industry, however it is not a solution to all problems. A few lines of Herculex Products do have activity on black cutworm, however none of the Bt lines can claim control of true armyworm.

All of these facts and more lead to the conclusion that we all must be vigilant in scouting for pest pressure and understanding pests life cycles and tendencies. Hopefully you can find some help in information such as these posts, and as always feel free to contact me for any additional assistance you may need.

IPM BULLITEN

Penn State Extension in Franklin County has established a grid of eight trapping sites across the county to attempt to survey populations of black cutworm and true armyworm moths. We previously reported that true armyworm moths have been found in the St. Thomas area in large enough numbers to call for added scouting in that area. Now we have detected economically significant flights of black cutworm in the St. Thomas area. Growers in the vicinity and surround areas should be aware of a heightened risk to their corn fields. Note that corn fields planted following soybeans can often sustain heavier populations of black cutworm caterpillars.

Now that significant flights have been detected we can begin accumulating degree days. Cutting behavior of black cutworm caterpillars is expected 300 growing degree days after the significant flight. The Penn State Agronomy program in Franklin County has recently established a weather station in Chambersburg Pa and will be tracking growing degree days. This bulletin will be followed by another once we begin to approach the 300 growing degree days. When the second bulletin is received, folks should start scouting corn fields to look for cutting damage. Economic thresholds for treatment are 2, 3, 5, and 7 cut plants per 100 for seedling, V2, V3, and V4 respectively.

Treatment options for at-risk areas vary but can include higher rates of neonicotinoid seed treatments where corn has not been planted and planting lines of Bt corn with activity against black cutworm if seed is still needed; however, growers should recognize that neither of these options are completely effective. The most economical control method for cutworm is scouting fields and applying rescue treatments where cutting activity exceeds economic thresholds.

More information on this pest can be found online at http://ento.psu.edu/extension/factsheets/black-cutworm , or by visiting the local extension office. Please share this information with others who may be interested in it. Again it appears that the pressure at this point is limited to the greater St. Thomas area. I will continue to keep you up to date if populations build elsewhere.

IPM Bulletin

Penn State Extension in Franklin County has established a grid of eight trapping sites across the county to attempt to survey populations of black cutworm and true armyworm moths. Both species have now been found in the county; however, black cutworm moths have not been found at threshold levels. True armyworm moths have been found at most sites with the most in the St. Thomas area, which had 10 moths last week. Other sites had two or less. These findings suggest that populations may be heavy in the greater St. Thomas area for true armyworms and special attention should be given when scouting and making recommendations in this area.

One of the most important management considerations when dealing with true armyworm is to make sure in areas where you have cover crops or heavy weed cover that you allow a 2 week period after the plants are dead until you plant. This would lead producers trying to get a timely planting of corn who have yet to spray to use a quick killing herbicide such as gramoxone instead of glyphosate.

Once corn is established scout fields closely, especially where heavy cover was. If you find more than 10 percent of your corn in a given field has an infestation of armyworms treatment is encouraged. Armyworms typically are found hiding in the whorl of corn during the day and their feeding creates a ragged looking leaf. In bad cases the leaves will be fed on until nothing but the mid-rib is left.

More information on this pest can be found online at http://ento.psu.edu/extension/factsheets/armyworm, or by visiting the local extension office. Please share this information with others who may be interested in it. Again it appears that the pressure at this point is limited to the greater St. Thomas area. I will continue to keep you up to date if populations build elsewhere.

Wheat Fungicide Trials

As some may know Penn State Extension is continuing a wheat fungicide trial and we have a site in Franklin County. This trial is looking at early applied (Feekes 5-6) fungicide with a follow up at emergence to the typical fungicide application at boot to emergence. So far there are no notable differences among treatments but it is interesting to note that powdery mildew is present in all treatments. The severity of the infection is quite minimal so little can be said about performance among treatments, however it is present. Dr. Collins of our SE Research station, a pathologist by training, has stated that this fungus likes 50-70 degree weather the best so if it warms up significantly it could slow the infection. Looking ahead at the forecast it appears in the near future we will likely keep conditions favorable for infection. If you are scouting for this pathogen look for lesions as noted on the bottom leaf in the photo. These lesions will have a small amount of white 'fuz' in and around them. This may be visible with the human eye but you can definitely see it with a 10x hand lens. I will keep you up to date as this study continues to unfold.

Cutworm Moth Trapping Update

So the first moth has been caught. My colleague Jeff Graybill in Lancaster County got a moth this week. When I check the Franklin County traps this week I did not have any moths but it appears we may start finding them. Just a reminder that this does not mean we are at a threshold of moths just simply that they appear to be starting their yearly trek northwards. I will keep you up to date on the progress of these as well as what it means as far as treatment etc. If you want to check out the data yourself as we progress remember to check out PA PIPE. This website has a plethora of information for pest management.

IPM Network Established

This year I will again be capturing moths to attempt to follow and predict activity. This spring I will be trapping Black Cutworm Moth as well as Armyworm. Many times blanket applications of insecticide are put down to act as an insurance against early season pests such as black cutworm, but is this really needed and thus economical. Last year my site in Franklin County never reached the threshold level of moths to feel that we had enough pressure to worry with cutworms. I also didn't hear of any issues with cutworms locally, but that doesn't mean they didn't happen. The question arose from this study last year, how irregular can these moth patterns be over large areas? In other words, if I scout one area of the county do I really get a full picture of the pressure? Well with the hope to answer this question this year I'll have 8 trapping sites across the county. These sites will be located in State Line, Mercersburg, Mont Alto, Chambersburg, St. Thomas, Shippensburg, Path Valley and Pleasant Hall Areas. Hopefully we will see uniformity in numbers and times of catches with these traps. I will also be updating you on what the pressure is like via this blog. Hopefully we can get great data off of this and start minimizing our reliance on 'insurance sprays.' This will save on our bottom line as well as possibly preserve beneficial insects that can help us control some of our pest populations.