Posts Tagged ‘20:1’

First Split Nitrogen Application to Small Grain

Friday, March 2nd, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Many wheat and barley fields that were not fertilized with manure or poultry litter last fall have looked poor for much of the winter. Even those fields that received some fall nitrogen (N) fertilizer but as commercial fertilizer have been yellow since mid-winter or earlier. Recently, the date when spring fertilizer can be applied was moved to earlier in February to help those with wheat that was showing signs of N stress and was trying to start spring growth. Since then, some cooler weather has settled over the region and slowed greenup in small grains.

For those who have not yet applied the first shot of N to their wheat, it is time to apply it. In fields that did receive fall manure or litter, the need is not as critical. In wheat, we have often seen about a 5 to 7 bu/acre yield increase when N applications are split into early greenup and then just before or at Feekes growth stage 5 when the first node is visible or can be felt above the soil surface. In work that Bob Uniatowski and I conducted a number of years ago, this response to splitting N applications was fairly consistent across locations and years. The largest response to a split application comes when significant rainfall occurs between the two splits causing some of the applied N to be loss either through leaching or denitrification. We also found that if all N was applied at one time, the early application date was the best choice although if the wheat had adequate tiller numbers in early spring even a Feekes growth stage 5 single application could produce excellent yield potential.

For those who may be growing barley, we did find that this crop is very sensitive to the rate of N applied because the straw strength seemed to be most affected at high rates of N. Whenever we applied much more than about 80 pounds of N per acre, we started seeding significant lodging which can not only make harvest difficult but can cause yield reductions, especially when lodging occurs early in the grain fill period.

Nematode Sampling for Soybean

Friday, March 2nd, 2012

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

This is not a good time to take nematode samples for root-knot nematode detection but if soybean cyst nematode (SCN) is a concern and you are planting soybeans this spring it is not too late to sample. SCN is detectable all season long as long as the ground is not frozen or flooded. Remember that snap beans are also a host of SCN and fields planted to snap beans should be checked for SCN. Lima beans are resistant to SCN. Testing most of the major baby lima bean cultivars confirmed that they are resistant to the major race or genotype of SCN that is prevalent in Delaware.

Nematode sample bags are available at all the county Extension offices as well as the information sheet which needs to accompany each sample. This info is also available online at http://ag.udel.edu/extension/pdc/. Samples do not have to be submitted in these bags but are there for your convenience. Soil samples for nematode detection should be at least 2 cups of soil placed in a Ziploc plastic bag. Do not use paper bags unless they are double-bagged with a plastic bag.

Small Grain Diseases

Friday, March 2nd, 2012

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Powdery Mildew on Small Grain
Be on the lookout for powdery mildew on ‘Thoroughbred’ barley and wheat. Powdery mildew has been seen on both within the last several weeks. ‘Thoroughbred’ barley is very susceptible to PM as you know and if the stand is thick and lush you will more than likely see it. Does it need to be controlled this early in the season? I think it depends on how many times you are willing to spray it. Dr. Arv Grybauskas did a trial last season looking at fungicide applications at jointing (GS6), flag leaf emergence (GS9) and flowering (GS10.5) Tilt (4.0 oz/A) was applied at GS 6 or 9 and Prosaro (6.5 fl. oz/A) was applied at GS 10.5. While all treatments gave a positive yield response in two trials, only the later applications gave a significant yield increase. It confirms what we have been saying about the importance of keeping the top two leaves free of disease and the positive relation to grain fill. This is true in wheat and susceptible barley like ‘Thoroughbred’. If you spray to control mildew at jointing you may have to come back again later because the control will not last season-long. Disease control later is more important for protecting the yield potential of the crop.

For powdery mildew on wheat, check areas of rank growth first to see if the disease is present in the field then revisit to see if it spreads. It is too early to consider control of powdery mildew (PM), but if it is present, keep scouting. Unless the variety is very susceptible the mildew does not move fast depending on the weather.

Rank areas, like the one pictured here that was infected with powdery mildew, should be checked often.

Close-up of powdery mildew as it looks now

Rust on Small Grain
Everyone has been wondering about the possible consequences of the warm winter and one consequence might affect wheat. Both leaf rust and stripe rust have been found in the South this winter. It has been mild and relatively moist depending on the location. This scenario is conducive for rust infections that get started in the southern production regions and blow north as the season progresses. With the early appearance down south, the mid-Atlantic area may see rusts early enough to be a threat. Keep your eyes open as the season progresses.

Western Bean Cutworm Verified

Friday, March 2nd, 2012

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

We recently received verification by a USDA identifier that the moths we sent off for identification we collected in our 2011 survey were Western Bean Cutworm (WBC). The counts were extremely low and no damage was observed to corn ears but this is a pest we will need to watch for in field corn and sweet corn. Adult moths fly in mid-summer and females lay eggs on the upper surfaces of corn leaves. Unlike Black cutworm that feeds on seedling stage corn, this is a later season corn pest, which feeds on tassels, silks, and developing kernels and can cause severe damage. Factors that contribute to the risk of potential problems include: (a) sandy soils, (b) a high percentage of acres in reduced and no-till production, (c) high humidity, and (d) presence of multiple host crops. Since these conditions fit Delaware, we will need to watch and see if this insect becomes a serious pest over the next couple of years.

The following is a link to pictures of the moth, larvae and damage to corn as well as potential management options. http://ipmnews.msu.edu/fieldcrop/fieldcrop/tabid/56/articleType/ArticleView/articleId/3195/Western-bean-cutworm-control-considerations-for-2011.aspx

Seed Corn Maggots Control in Field Corn

Friday, March 2nd, 2012

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

With the warm winter conditions, we have observed flies actively laying eggs earlier and for a longer period of time. Adult flies are active in temperatures down to the mid 40s so it very likely that maggot populations could be higher in early planted field corn. Conditions that favor egg laying activity include decaying cover crops, high organic matter, freshly plowed fields, and/or manure applications. Control options include commercial applied seed treatments, or soil insecticides. It should be noted that seed treatment labels indicate that they only provide early season protection of seedlings against injury from seed corn maggots.

Avipel Section 18 Request for Bird Management in Field Corn

Friday, March 2nd, 2012

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Our Section 18 request to EPA for the use of Avipel as a hopper box seed treatment for bird management in field corn was submitted by the Delaware Department a little over one month ago. Since the review period for Section 18s is a minimum of 50 days, we do not expect to hear back from EPA before mid-March. I want to thank all who responded to our survey – we received a fairly good response rate as well as very good information from all who were able to respond. We will let you know as soon as we hear from EPA about our Delaware submission.

Strawberries, Row Covers & Freeze Protection

Friday, March 2nd, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Row cover management in plasticulture strawberries has been difficult this year due to the mild winter. In normal winters, row covers applied in December serve as winter protection to limit stand losses, dessication damage, and low temperature damage to buds. While plants are in a dormant state or when buds are not yet active in strawberries, the buds can tolerate temperatures down to 10°F.

Removing row covers during warmer winter periods can help to delay bud activity and reduce susceptibility to later freezes. Replace row covers in times when freezes are expected. Highest yield potentials are usually obtained by uncovering and covering in the late winter and spring based on expected temperatures when compared to the practice of keeping row covers on continuously into the flowering stage.

Once buds have begun to emerge, even when tight, they can only tolerate temperatures down to 22°F. As they begin to open, the critical temperature for damage increases (popcorn stage 26°F, open blossom 30°F).

For growers that have not been taking row covers on and off and will be leaving them on until bloom, the potential for losses due to freeze events will be greater during March due to the increased bud activity. Prior to forecasted freeze events, check the plant bud stage, and apply additional freeze production to limit losses. This may include double covering with row covers (2 layers), or the use of low volume sprinklers through the night and into the morning as a frost protection over the row covers. Loss of buds or flowers due to freeze events will reduce yields and profits substantially. A single 1.2 ounce floating row cover will give about 4 degrees of protection.

Be Sure to Monitor for Spotted Wing Drosophila in Strawberry and Brambles This Year

Friday, March 2nd, 2012

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu

By now everyone should know that the newest invasive pest, the spotted wing drosophila (SWD), is here in the mid-Atlantic. It was found heavily infesting blackberries and raspberries in central Maryland this past summer and fall. Just about everywhere we trapped for it (I am still trapping adults in February in brambles, SWD overwinter as adults) we have found it on the western shore. We know it is on the eastern shore through trapping efforts by the University of Delaware. What we do not know about the eastern shore is how bad SWD infestations might be this coming season. The first crop that may get hit is strawberries. Information from Oregon and Michigan shows that their strawberries are not attacked to any great extent, but we DO NOT know what the fly may do to our strawberry crop. That is why it would be prudent to put SWD traps out and monitor for the adult flies. Males have a spot at the end of their wings (Photo 1), females do not (Photo 2), but the females do have a strong ovipositor they use to saw into non ripe fruit and lay their eggs—which is why they are such a devastating pest.

Most growers we visited did not think they had SWD on their farm and yet we found it everywhere we looked. The damage is often mistaken for early rotting berries or fruit (Photo 3). Early control is essential, if this fly is allowed to build its population through the summer into the early fall it will be very difficult to control and will be present on your farm basically forever. There are several web sites you can use to build your own traps (just Google spotted wing drosophila traps), or you could ask for help from me or your Extension educator about trapping. The key is to use a very common, inexpensive product as bait in the traps – apple cider vinegar. Traps should be placed in the field within the plant canopy, out of the sun if possible, and checked once a week for flies. Some traps should be located near the edge of the strawberry field and others along a woods edge. There will be many fly species in the trap, if you are not sure you have SWD take it to your local Extension educator for identification.

Photo 1. SWD adult male

Photo 2. SWD adult female

Photo 3. SWD damage to blackberries

Spotted Wing Drosophila Verified in Delaware

Friday, March 2nd, 2012

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

We finished our 2011 SWD monitoring activities in late September in a commercial vineyard and we did not detect any SWD adults in our traps. However, traps that were set out near the Milford area from September through December did collect flies which were verified by a USDA identifier in January 2012 as SWD. During the 2011 season, this pest made its way to Virginia, Maryland, Pennsylvania and New Jersey, so it was only a matter of time before their presence was confirmed in Delaware. As you start the season you will need to consider this pest when making management plans.

These flies can infest and cause a great deal of damage to ripening fruit, as opposed to the overripe and fallen fruit that are infested by most other Drosophila species. Females damage fruit by slicing through the skin with their knife-like ovipositor, and inserting eggs that develop into small white larvae. These cuts can also be a pathway for fungal pathogens, leading to greater reductions in fruit quality. Therefore, monitoring for SWD is important to avoid economic loss. This insect is a pest of most berry crops, cherries, grapes and other tree fruits, with a preference for softer-fleshed fruit. In areas where it has been detected, it is has become an important pest of cherries, raspberries, blackberries, blueberries, strawberries, grapes, peaches, and plums.

For more information on monitoring, identification and control of this insect pest, please check the following links:
http://www.ncipmc.org/alerts/drosophila.cfm
http://swd.hort.oregonstate.edu/

Pea Herbicides

Friday, March 2nd, 2012

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Weed control options remain limited for processing peas. Pursuit, at 1.5 to 2.0 fluid ounces per acre, needs to be used as a pre-plant incorporated or preemergence treatment and is used primarily for broadleaf weeds. Preemergence applications of Command at 8 to 16 fl oz or Dual at 0.5 to 1 pt/A are labeled for control of annual grasses and some broadleaf weeds. Basagran and Thistrol are labeled for postemergence control of broadleaf weeds. Apply Basagran at 1.5 to 2 pints per acre after peas have more than three pairs of leaves. Do not add oil concentrate. Select, Assure II, Targa, or Poast can be used for postemergence grass control.