Scout for Western Bean Cutworm (WBC) egg masses…

Contributed by Robert Moloney, Syngenta Seeds

WBC moth flights spiked last week so prioritize scouting of fields that are about to tassel or tasseled last week…

WHAT TO SCOUT:   WBC show a very strong preference for pre-tasseled fields, so any pre-tassel fields will have many more egg masses laid in them.  This doesn’t mean you won’t get any eggs laid in a field that is in tassel, but the majority of eggs will be laid in pre-tassel fields (if available) so start there.  Numbers seem to be higher in sandy soils or sandy areas of fields.  Make sure you scout at least 20 plants in each of 5 different areas of the field.  The more plants you check the better.

WBC egg mass

WHERE TO LOOK: egg masses are mainly laid on the upper surface of leaves in the upper part of the plant.  Most often it will be in the upper 2-3 leaves of the plant, and often on leaves that are still upright.  The moths seem to hide between the leaf and stalk during the day, so we are finding the majority of egg masses are on the leaf within 12 inches of the stalk (i.e. near the base of the leaf, NOT toward the tip).  There can be more than 1 egg mass per plant, and we are finding that when you find a plant with egg masses often neighbouring plants will also have egg masses on them.

WBC egg mass shadow - T. Baute

 WHAT TO LOOK FOR: as Tracey Baute from OMAFRA has suggested, one of the easiest way to find egg masses is to put the sun behind the plants you are scouting and look for shadows.  Most often round or irregular shadows on the leaf will be egg masses (see picture left).  If the plants are still short you can look directly at the upper leaves for egg masses.  The egg masses can range from the size of a penny to the size of a quarter so they are fairly easy to see.

The egg masses are made up of a large number of individual eggs laid together.  The eggs start out a pearly white colour, then slowly change to tan, and finally to purple as they are ready to hatch.  Stinkbug eggs can look similar but have a “crown” around the top that give them a more shiny, silvery colour.  Hatched WBC egg masses look like popped bubbles and have purple/blue colour.  The recently hatched larvae are quite small and will rapidly move into the whorl to feed on the tassel before moving down and into the ear.

WBC egg staging

CONTROL THRESHOLD: the threshold for spraying WBC is 5% of plants with egg masses on them.  Spray application should be timed to egg hatch.  Once the larvae have moved into the cob chemical control is not possible, so timing is important to catch them on the leaf or in the whorl still.  Matador™ insecticide is registered for WBC control (including for aerial applications).  Keep water volumes up to get as much coverage of the plant as possible.  Since pyrethroid type products are less effective as temperatures increase, spraying in the evening or on a cool day will help improve control.



What’s bugging my soybeans?

By Robert Moloney, Syngenta

We’re seeing all kinds of things happening in soybeans right now.  Here are some of the insect issues you might run into:

SOYBEAN APHIDS: Cruiser Maxx seed treatment will provide excellent early season control of soybean aphid, but many soybean fields are now getting to a point where the Cruiser is running out of steam.  The hot dry weather we are experiencing is very conducive for aphid numbers to build very quickly.  Scout your fields at least weekly to see if you have aphids moving in, and more often once you have established aphid populations.  Often aphid populations will first appear along tree lines where winged aphids may drop out of winds blowing across the field.  If temperatures are moderate look at the newer trifoliates on the top of the plant first as aphids love fresh and succulent leaves to feed on.  Under extremely hot conditions they may move down the plant into lower parts of the canopy.  Aphids are also attracted to soybeans plants suffering from Potassium deficiency (yellowing of the margin of the older leaves) so look in yellow areas of the field.  Watch for ladybugs or ants crawling on soybean plants and you’ll often find aphid populations on these plants or plants nearby.

Soybean aphids may or may not have wings but will always have 2 cornicles (look like tailpipes) coming out of their back.  The threshold for controlling aphids is 250 aphids/plant on 80% of plants and rapidly increasing numbers.  Natural predators (including ladybugs) may be able to keep them under control, but in dry conditions the sugars in the soybean plants become more concentrated which is super-fuel for soybean aphid growth and reproduction.  Matador 120EC is a great control option if needed.

TWO SPOTTED SPIDERMITES: This hot dry weather is also perfect conditions for a spidermite outbreak.  Usually we’ll see them move onto the soybeans/edible beans when the grasses in ditches/fencerows start to dry up from drought or as wheat plants mature and dry out.  Because of this they will often show up on the edges of the field first.  They can produce silk webs to catch the wind and move greater distances and end up in patches in the middle of fields too.  Spidermites are much harder to see than soybean aphids so scout for the damage first, then look at those leaves for the mites.  The damage caused by spidermites is stippling (small, pin sized whitish spots) on the leaves.  Severely infested leaves may have a bronzed or grey appearance to them (often it will start in a patch in the field).  The mites themselves will be on the underside of the leaves and you’re best to use a magnifying glass to see them on the leaf.  The other option is to shake the leaf over a piece of white paper and look for small (pepper size) dots moving around on the paper.  You may also see silk webbing on the underside of the leaf.

If you look at them with a magnifying glass you’ll see 2 black blotches on their back (hence the name) and that they have 8 legs.  Spidermites can be very damaging to yield if ignored.   Four mites per leaflet or one severely infested plant is the threshold.  If they are moving in from headlands and you catch them early enough you may be able to get away with only treating the edges of the field.  Cygon or Lagon are the products of choice for spidermite control.  Pyrethroid insecticides (such as Matador) can cause spidermite populations to flare up.  Damp/wet weather will help encourage diseases that can kill the spidermites.

RED-HEADED FLEABEETLE: this is an oddball that we rarely see in soybeans but they are out there this year.  Damage looks very similar to other fleabeetles (small areas round circles of the upper surface of the leaf scraped off).  The fleabeetles themselves are skittish and will jump/fly when disturbed on the plant.  They are shiny black and have a dark red head.  Threshold for these insects is the same as for most of our foliage feeding insects – typically not a concern until we lose 15% of the whole plant leaf area.  It would be extremely rare to see fleabeetle get anywhere near this level of damage in soybean, but even low levels of damage are very obvious in the field.

ALERT: high black cutworm levels in Parkhill and Watford areas

Eric Richter, Syngenta Seeds has seen several fields in these area’s with what he has described as “… the highest levels I’ve seen in my career…”.  In these cases the hybrids with no genetic protection (i.e. that don’t have traits such as Agrisure Viptera 3111) are being completely wiped out.  Make sure you are checking your fields especially if you are in a typically high risk area (north of Lake Erie).  See blog article below for more cutworm details.

There are lots of different insects and issues out there this year so make sure you keep an eye on your fields.

Plant Stand assessment – improved accuracy with measuring wheel.

If you have ever been frustrated trying to get an accurate plant population for an emergence issue using 1/1000th of an acre count there is a better method. For the last few years I have been using the measuring wheel method and have more confidence in my plant stands. The benefits of using this method are reduced ‘cherry picking’ of visually good or bad areas of the field, speed of count and improved accuracy of the count.

How does it work?

To use this method of population counts you push the measuring wheel and count 150 plants (I count by two’s, if you are really good you can count by three’s). When you reach a count of 150 plants, record the distance traveled in feet. Sorry no metric here record the measurement in feet. Repeat the count/measure three or four more times in the field or affected area. Average the measurement and convert using the following table by dividing the average number of feet for 150 plant count into the conversion factor. Example if I averaged 100 feet in a 30 inch row spacing the population would be 26,613 plants per acre (ppa) (2,613,600 divided by 100 feet = 26,136 ppa).

Also, assess non-emerged seedlings using the checklist in the Replant corn – How to decide article, by recording the population and the emergence issues we can make a good agronomic decisions for this year and future years.

Emerged Corn Herbicide Options

Due to the wet conditions this spring, the corn that did get planted is currently at pre-emergent to 1-2 leaf stage. If you were planning on making a pre-emergent application on emerged corn need please pay careful attention to their herbicide program so that you don’t risk crop injury and possible yield loss.*
So what are some of my options?
1. There’s still time to protect against yield loss from early weed competition. Going in pre to early post is the best choice to keep your fields clean during the critical weed free period.
2. Time is running short – choose a one-pass treatment that will take you through the season so you can avoid making a second application. One-pass and DONE.
3. Don’t spray glyphosate alone. Utilize a residual product(s) with your glyphosate to maximize your weed control, to reduce the need for a second application and help manage resistance on your farm.

For pre-emergent up to the 2 leaf stage of corn:
1) Stick to a pre-emergent application of Callisto® plus Primextra® II Magnum®. Or, if grassy weeds are getting beyond the 2-leaf stage in your glyphosate-tolerant corn, add in Touchdown Total®.

Beyond the 2-leaf stage up to 6-leaf corn (glyphosate tolerant corn):
If the corn crop has reached the 2-leaf stage, then switch to Halex® GT. Alternately, you could choose a tank-mix of Callisto + Primextra II Magnum + Touchdown Total for a one-pass contact and residual treatment.
*Refer to the label for a complete list of weeds, registered rates and timings. Please consult with your input supplier or local Syngenta representative for more information.

Replant corn – How to decide.

This year we had some fields that were planted early and then went thorugh a very wet, cold period and now the emergence is less than desirable in some areas of the field. Do I replant the poor sections, or the whole field (with the price of corn this would be a very costly option), do I leave it alone, these are all very good questions.

Corn replant decisions are difficult. The following table can be utilized as a guideline when assessing yield potential at various planting dates and populations. In general it doesn’t pay to replant corn where populations of healthy plants are greater than 18,000 plants per acre

First we need to establish the population that has emerged. You can do this by counting the number of plants in 1/1000 of an acre (see chart). Do this a number of times in the field. Also, assess the cause of reduced emergence using the following checklist.

 Rotted seed or seedlings
 Sprout twisted or leaves expanded underground
 Seeds hollowed out (insect damage)
 Check seed intactness (firmness)
 If seed is watery or “yellowy pus” it is not going to emerge
 Do not worry about crooks or turns of the coleoptile (shoot) as it may be responding to the seed orientation (corn seed does have an up and down side); also, cold soil will often disorient coleoptile growth.

As this is a very difficult decision please contact your NK field representative or seed dealer if you have any questions.

It’s time to switch

I have finally pulled the trigger and it is time to switch in all the Ontario corn growing area’s except maybe Essex County to a hybrid that is 100 – 150 CHU less than your normal maturity that you would plant. With the recent wet weather please work with your corn supplier to get the required seed to your farm. Be aware as this may take a couple of days as we are moving seed all over Quebec and Ontario to make sure you have the best seed option for your farm and situation.

Is it time to drop corn and switch to soybeans? This depends on each individual situation but you need to think about the following:
1) Do I have enough corn at 75% of expected yield to meet your delivery contracts this fall?
2) Do you need the production for feed?
3) Is the current fall delivery price worth the risk of reduced yields?
4) Herbicide or fertilizer is applied for Corn?
5) Do not want to risk changing my rotation?

Do you have other reasons to continue to plant corn, please include in the comments.

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