Mason County Extension detected soybean aphids in several locations throughout our territory earlier this week and while all observed populations were sub-threshold, producers should keep "an eye out" for aphids just in case.

We have also noticed that many of the aphids observed over the last week are roughly ¼ the size of a typical soybean aphid. In addition, these short-stature aphids are white or gray in color rather than lime-green in color. What are they and how should one factor them into current thresholds for treatment?

Soybean aphids progress through a fairly complex lifecycle. They overwinter as eggs deposited on buckthorn in wooded areas. These eggs hatch into small wingless female nymphs (young aphids) that proceed to feed on the buckthorn host. Minus mating, they give birth to live young that are also wingless and female. Once mature, this second batch gives birth to winged females that fly from woodland areas into soybean fields where numerous generations are produced until fall when winged females fly back to buckthorn, giving birth to "mating capable" females. These are soon accompanied by winged males (the first of the season originating in beans) that fly to buckthorn and mate with them. The resulting eggs serve as the overwintering stage for the pest. That description alone becomes rather tiresome.

Entomologists know that numerous generations occur simultaneously while aphids reside in bean fields. One can thus observe nymphs (young aphids), alatoid nymphs (nymphs with wingpads), apterous females (wingless females), and alate females (winged females). "In-field" soy aphid populations often also produce the "small, white to gray colored version" of soybean aphid mentioned at the beginning of this article. These are not immature aphids but are instead referred to as white dwarfs. Nobody truly understands the reason why they are produced. Hot, dry weather may be one factor leading to their appearance, but other factors likely play a role as well. Purdue University has suggested that short day length, varied nutrition, natural controls, etc., may all play a role in their appearance. They are thus generally believed to result from "stress" placed upon the population.

How should they be factored into ones aphid tally? At the moment, universities recommend that white dwarfs be counted just like any other aphid. We recommend this because we honestly don't know what to do with this atypical form of soybean aphid. While we recommend that they be counted "just like any other soybean aphid," we also recognize that these soybean aphids do not feed like their larger sisters/daughters.

Damaging soybean aphid populations consume more "sap" than what they can digest and exude the leftovers as a wet, sticky material termed honeydew. Our office has occasionally observed that plants are not covered with as much honeydew when white dwarfs make up the majority of the population. Mason County Extension therefore believes that an "exceptional presence" of white dwarfs further highlights the need for multiple scouting tours. U of I Extension states that 250 aphids per plant are needed in R5/pre-R5 stage beans to warrant control (R5 is achieved when one of the four uppermost pods contain BB-sized seed). Mason County Extension typically suggests that the population must be increasing when the field is reexamined three days later. We currently feel that the presence of significant white dwarf numbers in the soybean aphid population further accents the need for reexamination before treatment. Has the population increased/stagnated? Has the population become more dominated by white dwarfs? A "Yes" to these questions likely makes management less economically feasible. By R6 (green seed filling the pod chamber), U of I Extension does not recommend management of soybean aphids. Speed scouting methods are also available to estimate the need for aphid management. Contact Mason County Extension for information about this alternate scouting option.

Sudden Death Syndrome (SDS) has begun to make an appearance in Mason County. Although the size and scope of that appearance remains to be seen, evidence of SDS in our area once again provides an excellent opportunity to review information associated with the "all too common" late season disease.

Fusarium solani f. sp. glycines is a soil-borne fungus that overwinters as spores in both debris and the soil itself. It grows into root and lower stem tissue during the early spring and tends to do so when cool, wet conditions prevail at planting or within a few weeks of planting. It was first described in Arkansas soybean fields in early 1970s and only received a name about 25 years ago. The fungal culprit was discovered as the 1980s prepared to give way to the 1990s.

Around the time of flowering, stress – such as that caused by dry weather, rainfall, cyst nematode pressure, etc. – is believed to initiate the production of phytotoxins. These toxins when released cause small veins within the plant to become plugged resulting in decreased water and nutrient flow. Eventually glob-shaped chlorotic spots appear, scattered about, on the leaf tissue. These spots then coalesce into larger yellow regions between the veins. These regions eventually die (turn necrotic) and may even drop from the plant. As the symptoms progress, the upper leaves drop from the plant leaving only the petioles attached to the stem.

The lower portion of the stem, near the soil line, may often be covered with bluish white fungal material, more appropriately termed macroconidia. While the pith of the root and stem remains white (unlike Brown Stem Rot – a disease capable of causing similar foliar symptoms characterized by brown discoloration of the stem tissue), the vascular tissue just below the epidermis takes on a red-brown discoloration. Infected plants may also develop less root mass than their uninfected neighbors. While not consistently noted in association with soybean cyst nematode, SDS is noted in conjunction with cysts in approximately 2/3 of all cases.

Recommendations to reduce yield losses from SDS include: targeting soybean planting for the first full week of May at the earliest, varying the maturities planted by an operation (in an effort to spread risk), increasing drainage, decreasing the stress associated with SCN and other pests, minimizing soil compaction, and utilizing the tolerance and partial resistance that is available in soybean varieties.

What will the impact of SDS be in 2008? The next week to ten days will tell the tale. If SDS becomes a common windshield observation by then – it will have been a good year for SDS and a rougher year for beans.

SDS is not the only disease currently observed in bean fields. Additional irregularities include:

BACTERIAL BLIGHT - Ragged, tattered, brown-speckled soybean leaflets are showing up in some fields in the central part of Illinois. Bacterial blight is caused by the bacterium Pseudomonas syringae. This bacterium over winters on residue and can also, sometimes, spread via infected seed. The bacterium is transported to the plant when it is blown and splashed onto the surface of soybean trifoliates. During wet weather, the bacterium enters the leaflet either through the water regulating stomata or, more typically, via wounds.

DOWNY MILDEW – Caused by the fungus Peronospora manshurica, this disease primarily overwinters in infected leaf tissue and is transported by wind. Humidity favors the disease. Small yellow green areas form on the upper surface of the leaflet and are accompanied by a mass of gray velvet-like fungal materials.

VIRAL DISEASE – Viral disease is an annual appearance in many soybean fields. Diseased plants may be stunted and often display either crinkled leaves or mottling of leaf material. The vector (mode of transportation) varies depending upon the specific disease in question.

All diseases, noted above, appear less than significant across the area although some individual fields may fight atypical pressure.

Recent tours of Mason County's Asian soybean rust sentinel plot have displayed thrips – what some might term an "aphid look-alike."

Thrips, like grasshoppers, are insects with an "incomplete" life cycle. In other words, the thrip egg hatches into a smaller version of the adult termed a nymph. The thrip nymph may vary in color from the adult but it has wings.

While the thrip lifecycle may be similar to that of the grasshopper, thrip feeding is very different from grasshopper feeding. Grasshoppers tear off large sections of leaf tissue, but thrips feed by "rasping and sucking." In this type of feeding, the thrip literally beats or grinds the leaf tissue with a retractable mouth part until sap begins to leak from the damaged cells. The thrip then inserts a needle-like mouth part into the "sap" and ingests it. The feeding damage usually appears as a host of small "thread thin", silvery lines or spots on the upper portion of infested leaves. Thrips tend to feed on portions of the plant where sap is made most available, such as the main veins of the soybean plant.

Thrips are roughly about 1/16" in length and are much longer than they are wide. The hyphen between two typed words would best appropriate the size and "first-glance" appearance of these insects. Most molt only a few times before they fall from the plant. They than pupate, emerge as adults and then lay small white eggs in green tissue. Those eggs later hatch into more nymphs and the process continues. Both nymphs and adults feed on the plants. While some species overwinter as adults in Illinois, such as certain species of grass thrips, those that attack soybeans are blown back into the area with thunderstorms.

The University of Illinois Extension recommends management in corn when "numerous" plants appear to be "silvered" by thrip feeding. In soybeans, thrip control is recommended when 25 or more thrips exist per leaflet.

During semi-drought conditions, their numbers can build and cause problems for producers but the amount of rainfall encountered in 2008 should negate the likelihood of thrips issues this season.

It is hard to believe that September is not that far away, harvest will be here soon, and the time to drill wheat is just around the corner. This also means that conversations must once again shift to a discussion of the Hessian fly.

The Hessian fly is deemed one of the more serious pests of wheat. Although it tends to cause more problems to our south, it is still deemed a significant pest of wheat in central Illinois.

Also known by the scientific name Mayetiola destructor, the Hessian fly is not native to the United States and was probably introduced accidently about the time of the Revolutionary War. It belongs to a family of insects that are known to form galls on plant material. While the Hessian fly may not cause large areas of callus growth, it does cause irregular growth in response to feeding by the pest.

Two generations of Hessian fly occur per year and the adult stage will begin to show itself soon. Those adults only live for a few days, but during their brief tenure they lay an incredible amount of eggs. Total egg counts per female may number from a couple hundred to several hundred and those eggs are deposited in clutches of a couple eggs to more than a dozen eggs. The eggs hatch within several days. The resulting larvae, correctly termed maggots, are initially red in color and quickly move to the area between the leaf sheath and stem of wheat plants. Over time, the larvae turn a gray-white color. The maggots must close in on the pupa stage of development by mid-autumn, forming a hard shell termed a "puparia," or they will not survive. Winter is spent in this "pre-pupa" stage that many describe as "flax seed-like" in appearance. The actual pupa stage is reached the following spring. Adults from this overwintering stage emerge soon after pupation, mate, and lay eggs resulting in the "in season" generation of Hessian fly.

It is the feeding of the larvae that cause the damage associated with this pest. As the maggots scrape away at the leaf tissue between the sheath and stem, they introduce a toxin that causes the plant to accumulate an excessive amount of sugar and also stunts the plant. This has a drastic impact upon yield and can also weaken the stem resulting in head loss.

Hessian fly resistance is available in wheat varieties, but the use of resistance alone is not adequate enough to manage this pest. Unfortunately, the Hessian fly tends to be fairly adept at overcoming resistance and can often do so within several years of introducing a new resistance package. Several biotypes, all with varying ability to overcome the resistance of different varieties, are known to exist. They are denoted by the letters A to O. The "L-biotype" of the fly was found to be fairly predominant in the southern part of Illinois a few years ago and can overcome a few resistance genes depending upon the wheat variety in question. Resistance should still be used, but it should be used while also abiding by the fly free date – a date when cold temperatures are typically deemed to have eliminated Hessian fly adults. In Mason County, the fly free date for wheat is September 29 to October 1.

Question: I have heard that wheat infesting aphids all transport Barley Yellow Dwarf Virus. Should I manage aphids this fall to avoid Barley Yellow Dwarf this spring?

Three aphid species are known to transmit the disease that we commonly refer to as Barley Yellow Dwarf Virus (BYDV). Those three species are 1) the bird cherry oat aphid, 2) the English grain aphid, and 3) the greenbug.

Bird cherry oat aphids overwinter in the state of Illinois as eggs deposited on cherry trees. Those migrating back into Illinois from the southern United States influence seasonal pressure more than their Illini-overwintering brethren. Once returned to Illinois, they first colonize small grains. They tend to feed on the lower part of the plant. They move to cornfields a few weeks post-tassel. Bird cherry oat aphids have a dark olive green head, thorax, and abdomen that is accented by a slight pink color on the tail-end. The aphid can produce toxic compounds that can injury the plant as they feed.

English grain aphids are perhaps the larger of the aphid species noted above. Capable of overwintering in thick stands of grass, they start to reproduce shortly after temperatures warm up in the spring. Light green in color they possess two very dark, tailpipe-like appendages commonly observed on the tail-end of most aphid species. Those appendages are termed "cornicles." Of the aphid species noted in wheat, they are probably the most common and they move back to grassy areas once their small grain host is harvested.

Greenbugs, while not noted as often, are the most damaging of the aphid species commonly blamed for transmitting Barley Yellow Dwarf Virus. They overwinter in the southern United States all year and migrate back into Illinois. Most likely a native of the former Soviet Union, the greenbug is light green in color and has a dark green stripe that runs the length of abdomen. The dark green stripe is actually the digestive tract, which can be observed through the aphid's semi-transparent exoskeleton. Greenbugs typically feed on leaf undersides and they are also capable of injecting a toxic salivary compound while feeding. Three to four generations of this aphid can occur per month with the typical female capable of reproduction within about 7 days of birth. Various biotypes of the greenbug exist and have thus allowed the greenbug to circumvent resistant varieties rather effectively.

Regardless of the species in question, all aphids possess the unique ability to reproduce minus mating. As a matter of fact, in-season aphids are typically all female, are all born pregnant, and all birth live young. This means that aphid numbers can literally explode in a relatively short period of time. All three species also can transmit Barley Yellow Dwarf Virus to wheat which can stunt and discolor the crop while also impacting yield severely. Fall infections, the result of fall aphid feeding, are deemed most destructive to yield, but the University of Illinois recommends drilling wheat after the fly free date to avoid BYDV- carrying aphids rather than the use of insecticides.

As harvest grows near, a review of a few commonsense safety tips appear to be timely. Following are a few farm safety reminders that will hopefully remind those in agriculture to consider safety when combines begin to roll. For those removed from harvest time activities, remember to drive safely and watch for slow moving vehicles.

Stalks, husks, straw, and grain are excellent combustibles. When combined with a little diesel fuel and oil, these materials contribute to some real fire concerns during harvest. Fire extinguishers are therefore a must on all equipment. Take the time to show the operator where the fire extinguisher is and how to use it correctly (i.e. aiming it at the base of the fire). Before harvest begins, all fire extinguishers need to be checked and charged as recommended by the manufacturer.

Dust represents another real, yet often forgotten, hazard on the farm at harvest time. If enough such material is breathed in, asthma, pneumonia, or general bronchial distress may result. Those helping with harvest should therefore minimize their exposure as much as possible. For instance, one need not stand over an emptying stream of grain if he or she can view that same stream from within the cab. In addition, rotating jobs may be a worthwhile idea. While providing a little diversity in harvest time experience, rotating jobs also minimizes dust exposure for those restricted to "dirtier jobs." A correctly used, tight fitting mask is always a necessity.

While taking time to shut down a tractor or combine during fueling may sound like a foolish, time consuming endeavor, producers should seriously consider a "time out" before fueling that allows the engine to cool down a little. Not doing so may spell a fire should fuel spill onto a hot block. At the very least, producers should keep a wary eye on equipment during fueling just in case a shut off fails resulting in a spill over.

Before harvest, producers should double check PTO shields, making sure that they are accounted for, present, and secured. If absent, get shields as soon as possible. Not doing so may mean a real slow down at harvest should an unshielded PTO result in loss of life or limb.

Keep little ones sequestered when equipment is on the move during harvest. While getting rest during harvest is wise, it is also hard to come by. As such, operators are less prone to adequately survey their surroundings. Combine a wearied operator with a few little ones figuratively (running about ones feet) and the product is a tragedy waiting to happen. Keep the little ones fenced in and always make sure someone is watching them during harvest.

Remember that experience varies on the farm. Not everyone has the same level of experience in the same breadth of tasks. Before assigning any task, mentally assess ones ability to accomplish the task safely. Take the time to review the task and safety concerns before starting regardless of time constraints, and if someone is not yet capable of accomplishing the assignment, don't be afraid to say "no" regardless of hurt feelings.

Double check lights on equipment. Lights that aren't "up to snuff" may seem of little importance curing daytime fieldwork, but a little dust and dusk can make less than adequate lighting a pain for the operator and a danger for everyone nearby. While at that task, one should double check reflectors and slow moving vehicle emblems.

Have emergency phone numbers ready and post them in shops, homes, and vehicles. Show each individual where those numbers can be found. Despite our best efforts accidents can still happen. Time is the critical factor at play following an accident. Decrease the time between the accident and the response, via prompt contact with those who provide emergency services and one you increase the likelihood of a positive outcome following an accident.