Category Archives: Grain

Wheat Closer To Harvest – Fusarium Head Blight A Concern

Wheat 011Here is a field in the northwest part of the county that is getting close to harvest. This field started with a less desirable stand, but you wouldn’t notice now. It is at milk stage progressing towards Feekes 11.3 where the kernel is hardening. There was a fungicide applied at heading, which has helped with disease. Rain in this part of the county is also much less than average, so this helps when disease is present.

Here is a brown stink bug on a head.  Sometimes wheat is infested with stink bugs during grain fill. The brown and southern green stink bugs may reproduce and have a complete generation in wheat before harvest. However, according to UGA Extension Entomologist Dr. David Buntin, they almost never require control. As wheat dries down, stink bug adults disperse to nearby summer crops. We would only treat if 1 or more stink bugs per square foot are present at milk stage. Treatment is not needed in the dough stage.

However, when wheat harvest gets underway, we need to pay close attention to the corn crop as stinkbugs will move to corn. UGA Extension Agronomist Dr. Dewey Lee says this could be a problem particularly around VT/R1 stage.  Corn is very susceptible to stinkbug damage at this stage. Dr. Lee recommends applying an a labeled insecticide by airplane rather than through the pivot.

Brown Stink Bug

Brown Stink Bug

Fusarium Head Blight – Dr. Dewey Lee, UGA Grain Agronomist (5/11/15)

The last four weeks, I have answered lots of questions about fusarium head blight, stagonospora glume blotch, tan spot, rust and even the possibility of cold damage on pollen from frost and loss of pollination.  All of these are potential causes of yield and test weight losses in small grains.  The biggest ‘killer’ though is fusarium head blight (FHB)…It will produce a vomitoxin called deoxynivalenol, more commonly called DON which in high enough concentrations will cause the grain to be rejected from the market. Over the last two + weeks, I’ve received a lot of samples or pictures which have demonstrated widespread infection of FHB.  As I stop and look at fields, it is evident that FHB is the major cause of our problems and the yield loss appears to be substantial.  Additionally, rye, barley and triticale are also affected by the disease.

Fusarium Head Blight

Fusarium Head Blight

The wheat fields that I have visited appear to have a 50+% loss. it is easy to see the shriveled, affected grains. Upon separation, the shriveled grains accounted for 50 to 65 % of the total grain set on the heads.  In most cases, even where growers applied two fungicide applications, yield loss from FHB is still high. I had hoped that we got by without much infection, but rain saturated the fields that flowered earlier as well as those that were still flowering, leading to considerable infection rates. Unfortunately, we can’t spray by air when it’s raining, misty or foggy…..which is the time we see high rates of infection.  You may read that Prosario , Proline , and others listed as preferred fungicides however, they are not 100% effective and by some accounts only 60 to 70%.

Leave a comment

Filed under Entomology, Grain

Stagnospora Glume Blotch

Wheat-Fusarium 002

Here are the symptoms on heads are from stagosnospora (formely known as Septoria) glume blotch on triticale. We will see dark brown or purple lesions form on the heads. Lesions are often more intense at the top of the flume, with brown blotches or streaks going down to the base of the spikelet. The central stem is often not affected. UGA Extension Grain Pathologist Dr. Alfredo Martinez says, “Stagonospora  usually diminish as temperatures warm up drastically or if dry periods occur. Strobilurin and triazole fungicides are highly efficacious in controlling the disease.”

Wheat-Septoria 004

Stagnospora Glume Blotch

I also saw spores from Pyrenophora or Helminthosporium causing Tan Spot (Yellow leaf spot or Blotch). Dr. Martinez says , “This disease is more problematic in susceptible varieties, poor fertility and in fields with wheat residue left on soil surface. Initial infections come from diseased crop debris in the soil, or from diseased grass hosts. Usually the lower leaves are infected first, and the disease progresses to the upper leaves and leaf sheaths if conditions are favorable. This disease develops over a wide range of temperatures and is favored by long periods of dew or rain. Crop rotation with non-host crops reduces the severity of tan spot. Seed treatment seem to be effective in reducing the disease. Fungicides applied timely are effective in reducing the disease severity and improving yield.”

Leave a comment

Filed under Disease, Grain

Grain Development In Wheat

Wheat 004

All wheat in Thomas County is heading and most if not all has been sprayed with fungicide. We want to protect the head and the flag leaf for disease, especially rust. Our wheat is in the Feekes 11.0 growth stage where the kernel is ripening. The grain fill period can last from 30 – 50 days depending on stress of environment. A low stress and high yield environment, it will take closer to 50 days.

Fusarium Head Blight

Last year was a bad year for Fusarium Head Blight. It infects during the flower stage, and we had wet conditions during that time last year. Wheat flowers 4 – 5 days after heading and lasts a few days. We are past flower stage now so possibility of head blight may only be for later planted or later blooming wheat. However, we are having the weather conditions that favor it, which you can see at the Fusarium Head Blight Prediction Center.

FusariumHeadBlight-Website

UGA Plant Pathologist Dr. Alfredo Martinez says about the use of chemical control:

“Control using fungicides can be difficult due to the specific time the fungicides need to be deployed and because selection of fungicides labeled for FHB is limited. Timing of fungicide applications is crucial for the control of FHB. Foliar sprays must be applied at the first sign of anthers extruding from the wheat (anthesis). Triazoles work best when applied right before or at early flowering on the main stem heads. The use of nozzles that provide good coverage of the spike is essential for proper disease management. The fungicides labeled for FHB disease-suppression only are listed in Table 3.″

Fungicides-HeadBlight

Leaf And Glume Blotch

This is another disease wheat can have during grain development. I wanted to share some pictures from Terrell County Ag Agent Nick McGhee he has seen on the Alabama line. Here is an excerpt from the UGA Wheat Production Guide:

Lesions (spots) are initially water-soaked and then become dry, yellow, and finally brown. Lesions are generally oblong, sometimes containing small black spore producing structures called pycnidia. The lesions are often surrounded by a yellow halo. Lower leaves are generally more heavily infected, with lesions joining together to cause entire leaves to turn brown and die. If pycnidia are present on lower leaves when the uppermost leaf and the head begin to emerge, infective spores will move to the top of the plant in splashing rain even after a brief shower. Symptoms may not appear for 10-15 days on the top leaves or glumes on the head. By the time lesions are seen on the head, it is too late for effective fungicide use. Therefore, it is important to examine the lower leaves for lesions when making decisions about fungicide application, not just the top leaves. Lesions are first tan or brown on the upper portion of the glume while the lower part remains green. As the head matures, it becomes purplish to black in appearance from glume blotch. Leaf and glume blotch can reduce yield as much as 20% and reduce test weight due to grain shriveling even when disease severity is low.

Leaf & Glume Blotch - Photo by Nick McGhee

Leaf & Glume Blotch – Photo by Nick McGhee

Leaf & Glume Blotch - Photo by Nick McGhee

Glume Blotch – Photo by Nick McGhee

 

Leave a comment

Filed under Disease, Grain

Wheat Rust In Mitchell County

Today, Mitchell County Ag Agent Andy Shirley discovered wheat rust in Mitchell County.Wheat leaf rust is caused by the fungus Puccinia triticina. Wheat rust has the greatest effect on yield of any disease because of its ability to develop quickly in the right environment. Rust pathogens must be re-introduced each year; they do not overwinter. The detection is by scouting. We have both leaf rust and stripe rust. Leaf rust has reddish postures on the leaves that you can rub off on your finger. Stripe rust postures coalesce to form stripes between the veins of the leaf blade.

Photo by Andy Shirley

Rust postules – Photo by Andy Shirley

We will have to treat with fungicides to manage rust disease. The most important thing is to protect our flag leaves. However, wheat is only in the jointing phase now. It is best to wait as close to flag leaf to spray – if rust is not in the field. At this time, we need to be scouting our fields for rust. If rust is found, then a spray is needed – regardless of crop maturity.

A good option is to mix our chemistries for a curative and protective effect and help manage for resistance. We have triazole and strobilurin fungicides available. UGA Extension Pathologist Dr. Alfredo Martinez says, “When leaf rust has become established in a field, triazole fungicides tend to be most effective. Strobilurins have a more preventive activity and tend to be weaker if rust is already in the field. Remember that protection of the flag leaf is of essential importance for yield preservation.” A complete list of wheat fungicides, rates and specific remarks and precautions can be found on page 60 of the 2014-15 Wheat Production Guide. More information on ID and control can be found at Identification and Control of Leaf Rust in Wheat in Georgia.

Rust spores - Photo by Andy Shirley

Rust spores – Photo by Andy Shirley

Leave a comment

Filed under Disease, Grain

Wheat Update

Wheat 011

I was able to get back into some wheat today and can see the crop is starting to look better. We had lots of nutrient deficiency with cold and rain over January and February. We planted also later because of being too wet at planting. We want to be on the look out for powdery mildew now. Berrien County Extension Agent Eddie Beasley has seen powdery mildew show up. This disease is not one we worry much about unless it reaches 2 leaves below flag leaf. Here is Eddie on video talking about Powdery Mildew Spotted In Wheat. I am also seeing aphids, but they are under threshold. Our aphid threshold at stem elongation before flag leaf is 2 aphids per stem.

Leaf Sheaths Strongly Erect

Leaf Sheaths Elongate

Wheat in this field is now approaching the stem elongation stage, Feekes Growth Stage 5. This stage is characterized by wheat standing erect and all tiller development discontinues. The growing point is still below the ground. According to Growth Stages of Wheat by Texas A&M, “The vertical growth habit is caused by a pseudo or flase stem formed from sheaths (part below blade) of leaves.” Below are more characteristics of this growth stage outlined in the publication:

After the appropriate amount of chilling, followed by resumption of growth, the growing point differentiates. This means that all leaves have been formed and the growing point…will begin to develop an embryo head. At this growth stage, the size of heads, or number of spikelets per spke, is determined. No effect on yield is expected from tillers developed after Feekes 5.0.

Leave a comment

Filed under Grain

Aphid Numbers Increase

Aphids-Oats 016

Aphids in Oats

 

Yesterday I looked at three triticale fields that are also grown for seed to check aphid presence. We’ve been talking a lot about the Barley Yellow Dwarf Virus (BYD) – a virus of small grain vectored by aphids. According to UGA Extension Grain Entomologist Dr. David Buntin, planting date is the most most important management practice of BYD. Small grain fields planted early (October 1-15) are more susceptible to BYD than later planted fields. Of small grains, oats are most susceptible to BYD. If we’re growing for yield, seed, etc, we need to be aware of aphids.

Generally, now is the time to apply insecticide for a treatment of aphids. Nonetheless, we still want to check for aphids 25-30 days after planting.

Young Greenbug Aphid

Young Greenbug Aphid

There are about five species of aphids present in our fields: bird-cherry oat, rice root aphid, greenbugs, corn leaf aphid, and English grain aphid. The aphids I am seeing are bird-cherry oat aphid and green bugs. The bird-cherry oat aphids are the most common vector of BYD, even though any species can vector the disease. The green bug is the only species that can damage leaves. Although this is minimal damage, it shows up as small purple/red marks on the leaves (below).

Aphid Feeding

Aphid Feeding

In wheat, our threshold of aphids during tiller stage is 6 per row foot. You can use this same threshold for other small grains. However, many fields were broadcasted, so check square footage instead. In all fields I checked I saw adult aphids and young, which means they are reproducing. I could also see aphids while standing up (usually I have to get down on the ground and hunt them.) I was also seeing many fat, red-orange aphid. This is a mummy aphid that was parasitized by a wasp (below, left).

Mummy And Live Aphid

Mummy And Live Aphid

Leave a comment

Filed under Entomology, Forages, Grain

Avoiding Grain Loss When Grazing

Oats 003

Here is some Coker 227 oats grown for seed but are also grazed. A critical decision that is make this time of year is when to stop cows from grazing so plants can produce seed. This decision is somewhat influenced by planting date but mostly by growth stage.

Oats Jointing

Oats Jointing

Small grains germinate and grow as seedlings before tillering. Following the tiller stage, the plant will begin the stem elongation phase. During this phase, the a node, or joint, will form at the base of the stem. This is a thickened area on the stem and is the growing point. If cows graze below the joint (growing point), this plant will not produce seed.

The first thing we want to do is look for joints. The decision to remove cows is based on grazing height and joint position on the stem. If joints are seen on stems but low to the ground and below the grazing height, cows do not need to come off the field yet. If joints are higher position and grazing is lower than joints, it is time to remove the cows. It would be a good idea to avoid grazing on a small area to observe growth the growth stage.

This field was planted in mid-November and is still in the tiller stage. Plants are 4-5 inches in height. We only found a joint on one stem, so this field can be grazed much longer removing cows.

Leave a comment

Filed under Forages, Grain, Livestock

Sidedressing Considerations

Our wheat is in the tillering stage, and now is time to sidedress. Wheat needs between 100 and 130 lbs of N in a growing season. We do not put all N out in the fall because we do not want plants to grow too much which will injury head during cold weather. The demand for N is low during the fall but increased just before stem elongation. We wait until January and February to put out most of our N before stem elongation. We put out recommended N at planting then finish our total N during side dressing. We count tillers and determine if we sidedress one or two times.

These tillers are like multiple stems that will each have a head. More tillers equals give us more grain heads which means more kernels and higher yield. Below is a picture of the tillers on this plant.

Wheat-Tiller-002

Wheat tillers

 

If wheat is drilled (usually 7.5 inch rows) then 19 feet of the row would equal a square foot. This field was broadcast, so I just checked random square foot spots. I count all tillers on the plants within that square foot. If we do not have 100 tillers per square foot, then we split side dress applications to the last week of January and the next application the second week of February.  If we have 100 or so tillers per square foot and good growth and don’t see much yellowing of the older foliage, we can wait until the 2nd week of February to put out all of our sidedress fertilizer.

Below is a picture of nitrogen deficient leaves. Since N is mobile in the plant, the lower leaves will turn yellow first. N and K are mobile in the soil also and will leach with rains.

WheatStreaks-Aphids 003

Nitrogen deficient leaves of wheat

 

Leave a comment

Filed under Fertility, Grain

Aphids Present In Wheat

I checked a small grain field yesterday afternoon and was noticing abundance of aphids. They were hit or miss a few week ago, but I am now seeing aphids each spot I stop in the field. Aphids are soft-bodied insects in the “true bug” family (Hemiptera) which means they have piercing-sucking mouthparts. They suck juice from the plant but are also disease transmitters. Barley yellow dwarf virus is a disease they vector. Wheat can be damaged but oats are more susceptible. BYD is present in most fields throughout GA and yield losses of 5-15% are common. Yield losses are greatest when plants are infected as seedlings.

Wheat-BirdCherry-OatAphids005

Wheat is tillering good now and standing 6-10 inches tall. At this growth stage, our threshold is 6 aphids per row foot. The field I was in was broadcasted, so its more difficult to count. At every location I checked, I was seeing 1 or 2 aphids on a plant. Since this field is at threshold, should be treated. The aphids I found were bird cherry-oat aphids, which UGA Extension Grain Entomologist Dr. David Buntin says is the main species that transmits BYD virus in the winter. A  lambda cyhalothrin pyrethroid such as Karate or similar product is recommended to treat for these aphids.

Bird Cherry-Oat Aphid

Bird Cherry-Oat Aphid

Leave a comment

Filed under Entomology, Grain

Cold On Small Grain

Cabbage-Frost 010

Cabbage-Frost 011Here is some wheat from last week that was showing some cold burn on the leaves. We got down to 21 degrees on Jan 8th. This burn will not be a problem in wheat since we are so early in growth stage and heads have not emerged. The main issue is slowing down growth. With forage crops, cold duration can hurt us since we are so slow in establishing our forage.  Seminole County Agent Rome Ethredge talked about leaves farthest from the ground have the worst damage. This is because water has a high specific heat, therefore moist soils will hold heat better. We may also see more damage where soils are dry for this same reason.

Leave a comment

Filed under Grain