Kevin H. Ganoe, Regional Field Crop Specialist, Central New York Dairy & Field Crops Team, Cornell Cooperative Extension of Chenango, Herkimer, Otsego,and Schoharie Counties
Weather Data for Week Ending Sunday, June 17, 2012
For the week ending June 17 corn growth has continued strong and early planted fields are in the V7-9 stage. Table 1 shows the average temperature was 2-3oF higher than normal. GDDs remain are above normal almost a full week. Table 2 shows rain below normal again this week and remains around normal for the season.
At the V7-9 stage the crown roots are developing rapidly. There are usually five nodes of roots below the soil surface and another set of roots above ground called brace roots. These brace roots also uptake water and nutrients and do brace the plant. Brace roots tend to grow out away from the plant providing more support as the plant grows taller.
It should take about 450 GDDs to get to that V5-6 stage and a new leaf should appear for every 70 GDDs accumulated. Looking ahead it should take 1250 GDDs for 96-100 RM hybrids and 1300 GDDs for 101-105 RM hybrids to reach tasseling/silking.
The long list of insects this growing season doesn’t seem to end…
But where did they come from?
As plentiful as rain was in 2011 the number of insect pests found this summer has seemed to be a never ending list. So far this year we have had damage from: alfalfa weevil, potato leafhop-per, black cutworm, armyworm and as of late several fields with wireworms. A question asked often is whether or not these insects are around because of a relatively mold winter because fewer were lost to a cold and snowy winter. The answer is no they are not.
Potato leafhopper, black cutworm and armyworm all come to the area on weather fronts from the south and west and do not overwinter. Wireworms are found in old sods so take care as you look to take on new land for corn production. Alfalfa weevil is a hold over from the year before and their extended presence seems to relate to an early start with warm weather in March but not to more insects surviving the mild winter weather.
The ongoing armyworm saga. Don’t stop scouting yet!
I would still continue this week to scout for infestations of armyworms. Even as of this past weekend I was still seeing damage to hay and corn fields. What can not be stressed enough is how widespread the armyworms are but only causing damage to a few specific fields.
Below is information that is a repeat of previous Checking the Back 40s but still applicable.
Over the next week you would be advised to continue to check the fields where armyworms are most likely to be found :
- grass or mostly grass hayfields especially those that are now second cutting fields and you may be looking at harvesting that second cutting soon. Even though second cutting fields are more likely, armyworms have been found in mature first cutting fields.
- corn fields that were late planted into grass fields, notill or tilled ground or fields planted into small grain cover crop.
- corn fields with grassy weeds, quackgrass and other perennials or even annual grasses like crabgrass. Fields that may be planned for post-emergence weed control and the grassy weeds get a little ahead have been a target in the past.
- small grain fields
Look for armyworms to be on the ground and undercover during the day, they feed at night. They won’t be in the ground but under any material they can find to crawl under.
Consider treatment if grass hay fields are have a consistent population of 3-5 armyworms per square foot range. Don’t just look in one spot, you may find 5 and then look other places and find none. Recommendations in corn are for at least 3 per plant in the whorl and they are less than ¾ of an inch then consider treatment. There is no reason to treat in preventative fashion for armyworms if they are not present. Also questions have been raised about second and third generation armyworms. There are second and third generations of armyworms in a summer but have never been know to be a problem. When the moths for the second and third generation fly off there are many places they may find attractive to lay eggs and is never as concentrated as in the first generation.
