Farmers and crop consultants are encouraged to complete this survey
This survey is intended to estimate the impact of pests on soybeans and currently used management strategies. Your perspective is valuable in making these estimates as accurate as possible. Your responses will be kept confidential and only aggregated responses for the state will be published. You can find last year’s estimates at https://midsouthentomologist.org.msstate.edu/Volume17/Vol-17-1_TOC.html.
Nicole Fiorellino | nfiorell@umd.edu Assistant Professor & Extension Specialist, Agronomy
The 2024 Maryland Corn Hybrid Trials results can be found at https://psla.umd.edu/extension/md-crops or downloaded at the link below. Many thanks to Louis Thorne, Gene Hahn, and Audrey Sultenfuss for their time spent preparing, establishing, collecting data, and preparing the report. These trials could not be completed without them. I greatly appreciate the Center managers and personnel who assist our team with executing these trials.
We are grateful for the funding provided by Maryland Grain Producers Utilization Board to support these trials. MGPUB provides our program with checkoff funding to support applied agricultural research and so we may generate results that directly benefit Maryland producers.
Reports are for crop conditions up to September 5, 2024.
Western Maryland
August brought us more rain than June and July combined. The hay and pasture fields responded, and there is hope for continued grazing and another cutting. The soybeans are probably the greatest beneficiary of the moisture. They are looking great as their pods fill. Modern varieties are a wonder to behold. Corn silage harvest began earlier this year thanks to the heat and drought. Many folks are glad they planted a little extra corn, primarily due to the need for forage and the low grain price forecast. Running it through livestock will add value. Triticale and oats are going in the ground for both fall and spring forage. Cool mornings and mild days have raised our countenance here in Western Maryland.—Jeff Semler, Washington Co.
Central Maryland
August has finally brought some much needed rain; although amounts have been scattered throughout the region. A storm last week caused crop damage in some areas of the region. While it won’t be a year for record-breaking yields, most of the corn and soybeans are looking fairly good. The majority of corn is in the dent stage and is starting to dry down. Silage chopping has begun. Full season soybeans are in the beginning seed stage (R5).—Kelly Nichols, Montgomery Co.
Northern Maryland
About 6” of rain fell in August, which really woke up soybeans, especially later planted beans and double crops. Unfortunately, the rains have ceased, with the last measurable rainfall coming over two weeks ago. Rain is predicted for this weekend, so fingers crossed for good rainfall to finish out what could be a strong late season bean crop. Corn is rapidly drying down and a few acres have been harvested but the majority of corn is still 25% moisture or better. We are about another 10-14 days before the combines are rolling hard. Tar spot was also confirmed in the region at the end of August, consistent with the two years prior. A lot of good dry hay was put up over the last two weeks.—Andy Kness, Harford Co.
Upper and Mid Shore
July’s much-needed rains tapered off, leaving August with sporadic showers that varied significantly depending on your neck of the woods. This inconsistency has led to some challenging conditions for crops. Signs of water stress have become apparent; soybean leaves are cupping and corn leaves are curling from lack of moisture. In response, center pivots on irrigated fields have been fired up again, helping to maximize yield potential after a brief respite in July. Corn is drying down, with some early-planted fields already harvested. Soybeans are also moving along, with early maturing varieties starting to turn and double crop beans filling out their pods. The dry conditions earlier in the season provided the perfect environment for Palmer amaranth to thrive and compete with the crops. They can clearly be seen towering over the soybean and even corn in both conventional and organic fields. The region has also noticed more spotted lanternfly activity as these pests hit their final growth stage and take to the air. While they’re mostly just a nuisance in agronomic crops, controlling them can really help out your local fruit and vegetable grower, who would surely appreciate the effort.—Dwayne Joseph, Kent Co.
Lower Shore
Corn is drying down, but harvest has not yet begun. Due to low grain prices, farmers are inclined to let corn completely dry in the field, rather than take a moisture price hit at the mills. Drought stress during vegetative and early reproductive phases hurt corn. Yield is anticipated to be poor, and ears look small. Soybean is looking better than corn, especially double-crop soybean planted after wheat. There have not been reports of serious pest or weed damage. Cover crops are being flown into some corn fields via airplane.—Sarah Hirsh, Somerset Co.
Southern Maryland
Conditions remain very dry across the majority of Southern Maryland. Corn harvest is in full swing with reports of average to well below average yields. Yields vary greatly within and between fields depending on soil type and where isolated showers happened to fall. Grain quality is a major concern this year. Growers are encouraged to get corn off as early as possible. Beans continue to put up the good fight. Many full season beans are yellowing and drying down. Double crop beans will need some more help to fill out pods. Farmers have been scouting for pod worms and stink bugs. Thankfully, only a few fields have reached threshold and required a treatment so far. Weeds continue to require attention as fields have taken longer to canopy if at all, allowing greater opportunity for weeds to gain their share of the limelight. We continue to see ragweed, pigweeds of all types, and morning glory present. Deer damage is readily apparent in later planted beans that are failing to re-grow or canopy following deer feeding. Forages have struggled this summer with many fields of cool season grasses requiring replanting this fall or next spring.—Ben Beale, St. Mary’s Co.
Andrew Kness, Senior Agriculture Agent | akness@umd.edu University of Maryland Extension, Harford County
Figure 1. Map of tar spot of corn for 2024 growing season as of September 5.
Our first official reports of tar spot have been confirmed in Maryland for 2024; almost exactly on pace for when we first detected tar spot in 2023 and 2022. The first report came from a dent corn field in Baltimore County on August 22 and subsequent reports were made from fields in Harford County on August 27 and September 4. All of these fields are near black layer and yield loss due to tar spot infection is not likely unless infection occurred earlier in grain fill or during pollination. It is not likely that we had tar spot infections occurring in July due to the extreme heat this year. Tar spot infections require lower temperatures than other common fungal diseases of corn such as gray leaf spot.
As average daily temperatures begin to dip into the mid 70s and mid 60s, tar spot symptoms will likely start to flare up in corn. Tar spot can spread as long as there is green tissue on the plant, which means symptoms can worsen even past black layer, making for a field that could look far worse than it actually is. For reference, last fall I did yield checks in two corn fields and one research plot that had fairly moderate levels of tar spot infection (Figure 2) but still yielded very well (220-300 bu/a), with the field with the worst symptoms topping 300 bushels. What likely happened is tar spot infected corn close to R5-R6 and it continued to spread after black layer since the plants stayed green beyond physiological maturity due to the stay green effect of foliar fungicides that were applied to these fields. Even though tar spot spores can blow short distances in the wind, if you are harvesting a field infected with tar spot, it would be a good practice to try to clean as much corn fodder off of equipment prior to moving to a new farm; a blower or air compressor will do the trick.
Figure 2. Tar spot symptoms on a senesced corn leaf.
As you are scouting your corn fields, be on the lookout for tar spot. With funding from the Maryland Grain Producers Utilization Board, we are conducting a survey of the distribution of tar spot in Maryland. If you have tar spot, or think you might, please report it to corn.ipmpipe.org or reach out to me at akness@umd.edu or (410) 638-3255. Reports are kept anonymous and individuals and/or farms are not identified in any reports, publications, or communications.
Andrew Kness, Senior Agriculture Agent | akness@umd.edu University of Maryland Extension, Harford County
Stalk rot (left) and ear rot (right) of corn.
With the dry then wet (then dry again) weather pattern we had this year, corn went through a lot of stress. Stressed corn is much more susceptible to ear rots and stalk rots. The degree of severity is dependent on a variety of factors, so it is wise to scout fields prior to harvesting in order to identify problematic fields and give them harvest priority.
Several different pathogens can cause ear rots in Maryland; the main contenders are listed in the table below. Although they typically do not affect yield, they can cause grain quality issues through the production of mycotoxins. Furthermore, if infected grain is not dried quickly or to a low enough moisture content, infection can spread, even when in the bin. Therefore, it is important to scout and identify fields that are infected with ear rots and harvest those first. It is better to pay a few cents in propane to dry the wet grain than to wait and risk infection levels getting worse, and the potential for elevated mycotoxin concentration in the grain. Quickly dry infected grain to 15% for short-term storage and to below 13% for long term storage and it is not recommended to store infected grain for longer than a year. It is important to note that not all ear rotting fungi produce mycotoxins, so I would recommend working with your Extension agent or crop advisor to get proper identification so that you know the species in question and thus if mycotoxin contamination is a concern.
Table 1. Common ear rots of corn.
Disease
Pathogen
Symptoms (see next page for pictures)
Mycotoxin
Fusarium ear rot
Fusarium verticillioides
“Starburst” kernels, white kernels, infected kernels may be scattered on ear
Fumosin
Gibberella ear rot
Fusarium graminearum
Ear covered in white mat often with pink hue, infection starts at tip and can progress to butt end of ear
Vomitoxin (DON)
Diplodia ear rot
Stenocarpella maydis and S. macrospora
White fungal mat on ear, may cover the entire ear
None
Penicillium ear rot
Several Penicillium species
Blue-grey spores on kernels developing on damaged ears (hail, deer feeding, insects, birds, etc.), may infect the germ of the kernel
Some species may produce mycotoxins
Trichoderma ear rot
Trichoderma viride
Green spores in between kernels
None
Aspergillus ear rot
Aspergillus flavus
Olive green spores on ear, usually starting at tip, associated with damaged ears (feeding from insects, deer, birds, etc.)
Aflatoxin
Stalk rots are also a harvest concern. Like ear rots, stalk rots are also caused by many different pathogens, several of which are listed in Table 2 below. No single factor causes stalk rots; they are rather the end result of a host of factors that contribute to a net deficit in plant carbohydrates needed for grain fill. The grain fill process is a major carbohydrate sink for the plant. As the plant produces carbohydrates through photosynthesis, it allocates almost all of it’s carbohydrate production to filling the kernels. A healthy plant will have sufficient leaf area to maximize photosynthesis and can therefore produce enough carbohydrates to fill the grain. However, when photosynthetic leaf area is compromised, the plant cannot make enough food to fill the kernels. In order to compensate for the deficit, the plant cannibalizes carbohydrates from existing tissues. The first tissues to go are the stalks, which are then easily compromised by stalk-rotting pathogens. Stalk rot is a byproduct of stressed plants during the growing season, particularly during grain fill.
Table 2. Common stalk rots of corn.
Disease
Pathogen
Anthracnose stalk rot
Colletotrichum graminicola
Diplodia stalk rot
Stenocarpella maydis
Charcoal rot
Macrophpmina phaseolina
Gibberella stalk rot
Fusarium graminearum
Fusarium stalk rot
Multiple Fusarium species
Any factor that reduces leaf area or reduces photosynthesis after pollination will predispose plants to stalk rots. These include reduced leaf area through insect feeding, lesions from foliar diseases, or mechanical damage (such as hail). Other factors include inadequate fertility, water stress, and excessive plant populations. Another significant factor is hybrid genetics; both resistance ratings to stalk rotting pathogens as well as ear and kernel size. High-yielding, large kernel hybrids are more susceptible to stalk rots if they are not kept healthy through grain fill.
Scout fields for stalk rots as early as black layer. The “pinch test” is one way to scout for stalk rots. Pinch the stalk in between the nodes at one of the lower two nodes. You should not be able to pinch healthy stalks, but rotted stalks will fairly easily collapse. Do this at several random locations to assess the field. Alternatively, you can do a “push test,” which involves pushing the corn stalks approximately 30 degrees from horizontal (8 inches laterally) at a height of about eye level. Healthy stalks will return to vertical while infected plants will not. If more than 10% of plants tested exhibit stalk rot symptoms, you may want to harvest as soon as possible or risk a not-so-fun harvest of lodged corn.
Reports are for crop conditions up to August 1, 2024.
Western Maryland
Welcome rains have sporadically arrived in Washington County. This has been the story for much of the summer. It depends on your location and how much rain you receive, out of which storms. Earlier in the spring, the southern part of the county was blessed more than the part that hugs the Mason-Dixon Line. July has seen that trend nearly turned on its head. Wheat is off, and test weights and yields were good. Many acres of optimistic double-crop beans were planted again. Moisture has dictated the success of those plantings. It is too soon to make any predictions on corn yields, but in many places, plants are shorter, but the ears might fill just fine. So we wait. In two weeks, choppers will start running, and corn silage will be our first indicator of yields. Peach harvest started a little early, and they are smaller, and yields are lower, but they are sweet.—Jeff Semler, Washington Co.
Central Maryland
Corn and soybeans are well into reproductive stages and further along than previous years. Most of the region has experienced drought conditions throughout the growing season. Some growers have begun chopping early corn silage given how far hot dry weather has pushed the crop. Very limited disease pressure throughout the region. Recent rains have been welcomed, where received. Most precipitation events have been sporadically distributed to say the least.—Mark Townsend, Frederick Co.
Northern Maryland
We ended July with around 3” of rain here at the Harford County Extension office. Rains were more periodic in July; however, that is not the case for the entire region—rains continue to be scarce the further west into Baltimore and Carroll County you go and the rain that has fallen across our region has been very scattered and localized. You can find corn that looks very good and you can find corn that looks very poor all in the same county. I do believe that most places are “holding on” in terms of yield—I think we will fare OK and we may have avoided a complete disaster but corn yields will certainly be off of our norm. Soybeans are flowering and look good; if they can fill all the pods they’re initiating then soybean yields should be strong; the next few weeks will make or break them.—Andy Kness, Harford Co.
Upper and Mid Shore
The first couple of weeks in July brought us more of the high temperatures we’ve been experiencing, but unlike June, we were finally blessed with some much-needed rain across the region. While some areas received more rain than others, it was all welcome. The timing couldn’t have been better, as most of the corn was entering the reproductive stages right at the start of the month. Due to this, late-planted corn is likely to yield better than the earlier-planted corn. Both full-season soybeans and corn are now in their reproductive stages. Most of the corn has finished pollination and is moving into kernel development. On the small grains front, yields were either on par with or lower than last year, with not many reports of fields outdoing last year’s yields. The recent rains have also triggered a flush of weeds. If you look out over the soybean canopy, you’ll see those notorious pigweeds, common lambsquarters, morningglories, and annual grasses making an appearance, especially in the lesser-managed fields.—Dwayne Joseph, Kent
Lower Shore
We have had periodic rains the last few weeks and much of the drought damaged corn is greening up. Farmers are optimistic that the corn will pull through and have average yields. The later planted corn the better, in terms of less drought damage. Most corn is now in reproductive stages. Some corn is being aerially sprayed with fungicides. Milo is heading out. Soybean also faced drought damage, but is looking good with the recent rains. Double crop beans are starting to take off with growth. Substantial weed or pest pressure has not been reported..—Sarah Hirsh, Somerset Co.
Southern Maryland
The region is finally getting some relief from the hot dry conditions we have experienced since June. Rain showers have been scattered, so some areas are better off than others. Unfortunately, some of the rains have come a bit late for corn which was past pollination. For the conditions this year, the crop overall looks much better than should be expected. Soybeans follow much of the same story. Many full season beans could never get off the ground with a lack of moisture and constant deer predation. These plants are now trying to canopy and flower but are way behind schedule for this time of year. Weeds, especially annual grasses, marestail, Palmer amaranth and common ragweed have taken advantage of the extra sunlight and lack of canopy closure to germinate. Many fields are speckled with these weeds coming in later in the season. Double crops beans struggled to germinate in the dry conditions or were planted late. They have made good strides in the last couple of weeks. Vegetable crops are coming off now with a consolidated harvest season due to the hot temperatures as of late squeezing the harvest window.—Ben Beale, St. Mary’s Co.
Reports are for crop conditions up to July 5, 2024.
Western Maryland
Dry, dry, dry. The pleasant spring has turned into a dry summer so far. Even when the heat isn’t oppressive, the sun is bright, and the wind blows all wonderful conditions for drying out things. Corn and full-season bean planting is a memory. Wheat harvest is in full swing, and yields and test weights are good. Two cuttings of alfalfa are off, and we are hoping for enough moisture to make a third cutting. Double-crop beans are going in the ground, further proving that farmers are the most optimistic people on the planet. Until next month, keep looking up. One day, those clouds will have rain in them, and we will need it.—Jeff Semler, Washington Co.
Central Maryland
The wet spring resulted in lots of slugs and replanted soybeans. However, in the last few weeks, the rain has disappeared here in Montgomery County. Temperatures have soared into the upper 90s, resulting in some very dry topsoil, subsoil which is quickly losing moisture, and drought-stressed crops. Some corn fields are starting to tassel, and soybeans are beginning to flower.—Kelly Nichols, Montgomery Co.
Northern Maryland
June was unusually dry and we are in a drought situation. Wheat and barley harvest and straw baling was a breeze to the dry weather, and harvest came about 1-2 weeks earlier than normal due to the dry, windy June. Yields were not near the record-setting numbers we’ve seen the past two years but they were still respectable. Having small grains off early will greatly benefit double-crop soybeans, assuming there’s enough moisture in the ground to germinate them. Earliest planted corn is in tassel by July 4 and we thankfully got a couple of decent storms just as tassels were pushing through and alleviated drought scenarios in many fields; that rain likely saved several bushels. Full season soybeans are also starting to come along nicely now after a slow start that some moisture is back in the soil.—Andy Kness, Harford Co.
Upper and Mid Shore
Center pivots have been working double time, keeping corn and soybean fields in the region irrigated amid the ongoing dry spell. Significant rain events are a distant memory, and the summer solstice has brought record heat, contributing to visible water stress symptoms on non-irrigated fields. All corn acres are planted, and early-planted corn is currently tasseling. Small grain harvest is progressing well, aided by the dry weather, which has extended the harvest window. As the small grain harvest wraps up, double-crop beans will soon be planted. Meanwhile, sprayers are busy applying post-emergence herbicides to fields to manage pre-emergence weed escapes, most likely due to the absence of an activating rain. Hopefully we get some rainfall soon.—Dwayne Joseph, Kent Co.
Lower Shore
We had a very dry couple of weeks. Crops were showing signs of drought stress with stunting and leaf burning in some fields. This was followed by a 2-4” rain event across much of the Lower Shore. Corn is approaching late vegetative stages, but not yet tasseling. Wheat has been harvested and double crop soybean planted.—Sarah Hirsh, Somerset Co.
Nicole Fiorellino, Assistant Professor & Extension Agronomist | nfiorell@umd.edu University of Maryland, College Park
With the recent dry weather, some corn sidedress applications have been delayed past the optimum application window, causing farmers to think about the necessity of a “late” sidedress application. Let’s discuss corn growth stages and nitrogen (N) utilization in the plant and summarize research findings of yield response to “late” sidedress applications. This information can be useful for farmers to decide how to make decisions based on profitability, which sometimes may mean foregoing a late application which may result in decreased yields.
What is the “short stave”?
I often quote Liebig’s Law of Minimum and the visual analogy of a barrel made of wooden staves to represent agronomic management decisions, specifically fertility decisions. The first step to correcting a growth problem, be it fertility or otherwise, is identifying the problem that must be corrected – determining the “short stave” of the barrel limiting its capacity. While the gut reaction to stunted corn that missed a sidedress application may be a N deficiency, the “short stave” could be dry soils. I have seen corn that visually improved this week just due to precipitation. If you have heavier soils, good organic matter, maybe used manure, your corn may improve as the soil is rewetted and some N in the soil makes its way to the plant, eliminating the need for a trip across the field. Further, a rushed N application without precipitation in the forecast is not useful, as the N will not reach the plant roots with water as its vehicle.
Defining a “late” application
Each farmer may have a different definition of “late” sidedress application, so we should clarify this term and translate it to corn growth stages. Corn sidedress application is recommended between V4 and V6, to provide N to the corn as it enters a rapid uptake phase through the rest of the vegetative growth stage, as depicted in Figure 1. As the plant tassels and enters reproductive growth, the plant shifts from soil N uptake to translocation of N stored within plant tissues to the grain [1]. Thus, VT is the “turning point”, where a sidedress application between V6 and VT could be characterized as “late” but one might categorize any application after R1 as “the point of no return.” Confirming the growth stage of your corn is an important point to consider when weighing the possibility of a late sidedress application.
Figure 1. Nitrogen utilization of corn crop by plant tissue across the growing season. Source: Iowa State University Extension.
Risks of a late sidedress
Beyond missing the optimum window of utilization of applied N by the corn plant, there are other risks to consider when weighing a late application. Taller corn with more canopy coverage runs the risk of physical damage to the corn as application equipment moves through the field. There is the risk of leaf burn with foliar product applied, although the use of drop nozzles could help minimize this. Moreover, the delayed application of N may have stressed the corn in the early growth stages, already decreasing your corn’s yield potential. This means that even with perfect conditions and unlimited nutrients moving forward in the growing season, the yield “ceiling” has already been lowered. So, the cost of an additional N application will not be realized in profit (increased yield) and the most profitable decision may to forego applying more nitrogen. Finally, no farmer wants to risk making an N application when there is potential for loss to the atmosphere or to nearby surface water. Including potential off-site losses of applied N not utilized by the crop into the decision-making process may help make a late application decision more clear.
Yield impacts with late sidedress – pre-tassel
Yield benefits with sidedress through late vegetative growth compared to no application has been observed in other areas of the country; with researchers at Purdue University demonstrating sidedress at V15 and even up to R1 showed improved corn yield compared to no sidedress application, but still significantly less than corn sidedressed at V4 or V6 [2,3]. Research performed at Ohio State demonstrated an N application up to V10 minimized yield loss [4] and results from Cornell indicated significantly decreased corn yield with sidedress at V10 compared to sidedress at V4, V6, or V8 but significantly better than corn yield with no sidedress application [5]. In Minnesota, where the growing season is shorter, a sidedress application at V12 did not result in increased corn yield compared to no sidedress or sidedress prior to V8, with the researcher attributing this to compromised yield potential from early season N deficiency [6]. While these data are not local, they illustrate the potential for rescuing a corn crop from total loss with a sidedress application while the corn is still in the vegetative growth stage.
Yield impacts with late sidedress – post-tassel
Limited research findings exist to evaluate corn yield response to N application post-tassel [7]. There is a potential for rescue with a post-tassel sidedress application where severe N deficiency is observed, but this decision should be balanced with the potential return [6]. The lack of research findings of a post-tassel sidedress application should indicate this practice may not be recommended to optimize corn yield, farmer profitability, or environmental benefits.
Conclusions
Multiple factors should be considered when weighing a late sidedress application, first, determining the “short stave” and considering it could be drought, not N deficiency, and second, confirming the growth stage of the corn. While there are risks associated with late sidedress application, namely physical damage to corn with application equipment or increased potential for N loss off-site, data support sidedress application up to the end of vegetative growth can result in corn yield between optimum sidedress application and no sidedress application. There is no research to support yield benefits with sidedress applications post-tassel. Farmers should understand that early season N deficiency may have limited corn’s yield potential and consider this point when making profitable, late season sidedress decisions.
Reports are for crop conditions up to June 6, 2024.
Western Maryland
I have a good friend who says, “I don’t have forty years of experience farming; I have one year’s experience forty times.” This spring has been just like that. We have had more moisture than last year, but then came the hot days, cool weather, and more moisture. Corn is planted, and the first cutting of hay is in the barn. Soybean planting is winding down, and grain harvest will be here before you know it, starting with barley. With the moisture we will see how much disease took its toll. Fungicide applications weren’t always as timely as we would hope because of the frequent showers. Until next month when harvest is underway it is then the story will be told.—Jeff Semler, Washington Co.
Central Maryland
Planting is almost complete. Slugs have been an issue; some soybean fields will need replanting. It was getting a bit dry, which did provide a good hay-making window. However, a thunderstorm is rolling in as I write this, giving us some needed moisture. Small grains are looking good. Summer annual weeds like pigweed, crabgrass, and foxtail are starting to take off with this warmer weather.—Kelly Nichols, Montgomery Co.
Northern Maryland
Spring has been a little challenging in our area. A dry spell in mid-late April made herbicide efficacy less than ideal, followed by several weeks of a lot of rain, which activated herbicides but prevented the timely termination of other cover crops. Early planted corn and beans are up and out of the ground, with earliest planted corn around V6 and getting it’s second shot of nitrogen. Rainy weather in late April early May delayed planting the remainder of the crop by about two weeks. These later planted fields are much further behind than usual but are looking good. There has been some slug damage present, it gets worse the further west you go in the region. Barley nearing harvest and wheat is starting to turn. There are symptoms of head scab but it remains to be seen how severe DON levels are in the grain. The wet weather has made it very difficult to make timely dry hay.—Andy Kness, Harford Co.
Upper and Mid Shore
Corn acreage is looking good, with a nice color and uniform growth. Depending on when it was planted, corn is in the V2 to V5 stages right now. Most of our full-season soybeans are already in the ground. As usual, rain across the region has been hit or miss, with some areas getting a lot more than others. These downpours might not be ideal, but they’re certainly better than no rain at all. Barley harvest is just around the corner. Summer annual weeds are popping up and are ready to impact yield potential. If your residual herbicide program hasn’t kept them in check, now’s the time for a POST application. And remember, using multiple modes of action in your tank-mix slows down the evolution of herbicide resistance in weeds.—Dwayne Joseph, Kent Co.
Lower Shore
has been planted and currently in emergence stage to around V4 stage. Corn is looking good, and being sprayed to combat early season weeds. Soybean planting is currently underway. In a few instances, early planted soybean (early April) had to be replanted due to slug damage. Wheat is looking good and drying down. Farmers are gearing up to cut wheat, which is earlier than anticipated.—Sarah Hirsh, Somerset Co.
Southern Maryland
As I write this, a very welcome rain is falling outside my window. As we move into the hotter days of June, the old adage that we are only a week away from a drought at any time is holding true. Two weeks ago it was too wet to get into fields and this week we have corn fields starting to show curling leaves and drought stress. In general corn is off to a good start with most sidedress N applications completed. There have been a lot of catch up full season beans planted in the last 2 weeks. Slug feeding has been minimal this year. Barley is drying down with harvest expected any day. Wheat will not be far behind. Ryegrass continues to be a challenge for producers in both burndown situations in corn and beans, as well as small grains. Many fields may need a harvest aid to kill the ryegrass and allow for timely harvest of wheat. Given the wet conditions following flowering, we are encouraging producers to get the wheat crop off as quick as possible to maintain grain quality.—Ben Beale, St. Mary’s Co.
Emily Zobel, Senior Agriculture Agent Associate | ezobel@umd.edu
University of Maryland Extension, Dorchester County
Corn
Continue scouting for cutworms and stink bugs. The threshold for cutworms is 2-5% cut plants up to the V5 stage and with active larvae present. Stinkbugs will move into corn as surrounding small grains are harvested. When scouting for stinkbugs, pay close attention to the thorax of brown color stink bugs as the beneficial spined soldier bug is often mistaken for the invasive brown marmorated stink bug. The spined soldier bug has a prominent spine on each “shoulder.” NCSU’s suggested threshold is 13 stinkbugs per 100 plants for V1-V6, 10 stinkbugs per 100 plants for V14-VT, and 28 stinkbugs per 100 plants for R1-R2. The most critical time to treat if between V14 to VT is just before the primary ear is exposed to avoid banana ear. Stinkbugs will likely be around the primary ear at this point so that should be the target of the application.
Soybean
Early-season defoliator pests that are active right now include bean leaf beetles, green cloverworms, slugs, and grasshoppers. Soybeans can typically withstand a decent amount of defoliation before yield losses occur. If defoliation reaches 30%, and you are finding one grasshopper per sweep or 2-3 bean leaf beetles per plant treatment may be advisable.
Figure 1. Bean leaf beetle with feeding damage on a soybean leaf. Photo by Adam Sisson, Iowa State University, Bugwood.org.
Alfalfa
Begin scouting for potato leafhopper. Ten sets of 10-20 sweeps using a sweep net should be taken in random locations in the field. A detail threshold for alfalfa is based on the plant size and cost of the hay can be found online but a general guideline is 3” or less is 20 leafhoppers per 100 sweeps, 4-6” tall is 50 per 100 sweeps, 7-10” tall is 100 per 100 sweeps, and greater than 11” is 150 per 100 sweeps. If the field is more than 60 percent bud stage or if it has experienced “hopper burn,” the alfalfa should be cut instead of sprayed. Fresh-cut alfalfa should not be sprayed as leafhopper adults tend to move out of the field when it is being cut.
Figure 2. Potato leafhoppers in a sweep net. Photo by Bryan Jensen, University of Wisconsin, Bugwood.org.
