Weed of the month for May 2014 is Ground Ivy

Ground Ivy  

Biology: Ground ivy (Glechoma hederacea), also known as creeping Charlie, is a very difficult to control perennial broadleaf weed. It can often be seen growing in the shade and invading turfgrass and other mowed areas throughout the United States. Ground ivy thrives in moist, rich soils located in shaded areas, but will grow in full sun as well. These traits combined with the ability to produce aggressive rooting stolons, tolerate low mowing heights, and shade/crowd-out surrounding plants, help to make ground ivy one of the most difficult-to-control turf weeds in lawns.

Identification: Ground ivy is a perennial broadleaf weed that invades turf through aggressive stolons that ‘creep’ below the turfgrass canopy. It forms very dense, mat-like patches that effectively crowd-out the surrounding turf. Like other members of the mint family, ground ivy has distinctive square stems with two leaves branching from each origin point (node) and emits a disagreeable odor when crushed, damaged, or mown. Leaves are round to kidney-shaped with prominent veins and broad rounded edges. These leaves are held above the canopy by long petioles (leaf stems) which can effectively shade and weaken the surrounding turf. Spreading stolons root aggressively at the node, further making ground ivy difficult to control. It produces flowers from April to June that are tubular in shape, purplish blue with red speckles, lobed petals, and are arranged in groups of three to seven. Ground ivy can often be mistaken for other broadleaf weeds such as common mallow or henbit. However, common mallow has rounded stems and sharply toothed leaf edges while henbit stems do not ‘creep’ along the ground nor root at the nodes.  

Kidney-shaped leaves with deeply lobed edges

Two leaves branch from each node

Dense arrangement of ground ivy leaves

 

Leaves held atop long petioles (stems)

Square stems, characteristic of the mint family

Spreads via aggressive prostrate stolons

Ground ivy regrowth via aggressive stolons

 

Ground ivy flowers

Cultural control: Because of its aggressive growth and establishment, there are very few cultural practices that have been observed to effectively control ground ivy. Management practices such as improving surface drainage, watering deeply and infrequently, and cultivating (aeration) compacted soils may hinder the development of ground ivy in favor of a more dense, aggressive turf. Nitrogen fertilization will also provide some reduction of ground ivy cover in turf.

Biological control: None known for specific use in ground ivy. Our preliminary research suggests that iron HEDTA (FeHEDTA) may be used to manage ground ivy with multiple applications.

Chemical control: Because of its aggressive nature and the survivability of stolons, there are no preemergence herbicide options for the control of ground ivy in turf although Gallery (isoxaben) can help reduce the ability of stolons from rooting which will slow the spread of this weed. As a result, management must focus on postemergence herbicides. Repeat applications of two- or three-way mixtures of 2,4-D, dicamba, MCPP, of MCPA may offer fair levels of control. Turflon Ester (triclopyr) typically provides better control. Additionally, products that contain triclopyr or fluroxypyr as one of the ingredients in a two- or a three-combination herbicide will work well. In warm-season turf, Manor (metsulfuron) can control ground ivy when applied in combination with a non-ionic surfactant (0.25%). Most of these herbicides require supplemental applications for adequate control.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist

Leslie Beck, Postdoctoral Research Associate

European Chafer is at the Root of Spring Grub Damage in Northern Indiana

Reports of spring white grub damage are relatively uncommon in most of the Midwest. However, the European chafer is a slightly different beast and seems to be more cold-hardy than other annual white grubs. This characteristic allows it to feed later into the fall and start feeding earlier in the spring compared to Japanese beetle and masked chafer grubs. It also tends to infest areas with no previous history of white grub damage, including low maintenance areas. Folks in Michigan have been dealing with insect for many years now, but it is relatively new to Indiana; with the adults of this species first being detected in Porter, Kosciusko and Allen counties during 2007. We have now linked recent reports of spring white grub damage in LaGrange and Noble counties to this insect meaning that populations are well established in these areas and are likely established throughout the northern third of the state. Spring grub control is difficult to achieve and the only realistic chemical options are trichlorfon or carbaryl. Even then, repeated application may be necessary. If you notice white grub damage this time of year, take a closer look and try to find the larvae in the soil.

European chafer larvae can easily be identified using a 10X hand lens to inspect the raster pattern (shown above). Once established these insects may require some special attention going forward as they tend to be more damaging and somewhat less susceptible to traditional insecticide treatments. The best control is achieved using a preventive approach with applications of imidacloprid, thiamethoxam, clothianidin or chlorantraniliprole applied June through mid-July. Keep records of any European chafer infestation so you can identify areas to watch down the road.

Doug Richmond, Turf Entomologist

Weed Management is a Prerequisite for Using Neonicotinoid Insecticides

Honey bees and other pollinators forage for nectar and pollen on a wide range of flowering plants, including some of our most common turfgrass weeds such as dandelion, white clover, ground ivy, speedwell, chickweed and a host of others.

If any of these flowering weeds are present at noticeable levels, it may be wise to avoid treating the area with a neonicotinoid (or any other insecticide). In the case of neonicotinoids (imidacloprid, clothianidin, thiamethoxam, dinotefuran), mowing off the flowers before application may not be enough since these insecticides are systemic and may be taken up by the plant and translocated to the flowers when another flush of growth occurs. Lawns that are relatively weed free should not pose a substantial risk to pollinators should a neonicotinoid be applied. Effective weed control should be a prerequisite for using neonicotinoid insecticides. We simply don’t know how much of the material ends up in the pollen and nectar of our most common weeds, but if there are no flowering weeds to take up the insecticide, the risk to pollinators will be significantly reduced. Always avoid spraying insecticide of any type directly onto plant blooms.

 
Doug Richmond, Turf Entomologist

Early Season Caterpillar Update

Most of Indiana experienced cooler than normal temperatures over the last week, with good amounts of precipitation providing very good growing conditions for cool-­‐season turf. However, green-­‐up of warm-­‐season grasses has been slow, so we have a relatively mixed bag for insect development and damage. The cooler temperatures and ample rainfall should help mask insect feeding damage in cool-­‐season grasses caused by caterpillars such as black cutworm and armyworm while warm season grasses may be slow to outgrow such damage until warmer weather arrives. Warm-­‐season grasses could also be experiencing delayed green-­‐up due to the feeding activity of hunting billbug adults which seem to be out in force. Unlike the bluegrass billbugs that only cause significant damage in the larvae stage, hunting billbug adults may actually damage warm-­‐season turf, especially when green-­‐ up is slowed by cooler temperatures.

Click on the image to zoom in

The black cutworm risk map (above) has been updated to indicate high risk areas where larval development is likely to have reached the point where damage may be visible. Golf Course Superintendents in the entire southern half of the state should be scouting for this insect and paying attention to suspect areas on closely mowed turf.

Superintendents and lawn care professionals alike should keep an eye open for armyworms. They may be small right now, but as they develop, larger larvae can make a lawn disappear practically overnight. The most susceptible turfgrasses tend to be located adjacent to weedy or unmanaged areas, fence rows, the borders of agricultural fields and ditches where tall grasses provide excellent habitat for the adult armyworms to lay eggs. Check my previous tweet for insecticide recommendations appropriate for cutworms… the same chemistries will also be effective against armyworms.

Doug Richmond, Turf Entomologist

Rounds 4 Research

Rounds 4 Research is an innovative program aimed at generating resources to fund research and help ensure golf’s future. The premise is simple: Golf facilities can support the effort by donating rounds of golf for two or four or “stay and play” packages and other items that will be auctioned off online to generate funds for turfgrass research. Rounds 4 Research is administered by the Environmental Institute for Golf (EIFG) and presented in partnership with the Toro Co. The EIFG is the philanthropic organization of the Golf Course Superintendents Association of America.

Each of GCSAA’s 100 affiliated chapters, as well as local turfgrass foundations and other industry partners, will have the opportunity to solicit donated rounds. The EIFG will then distribute monies back to the participating organizations to fund research in their local areas. The Purdue University Turf Program is currently working with local golf course superintendent chapters to help them promote this program. Dr. Aaron Patton, Purdue University Turf Program said that "with grant funds becoming more and more difficult to secure, this program is a great way that local superintendents as well as Purdue University alumni can help support Purdue turf research."

Whether you are an organization looking to solicit rounds or a golfer looking for the opportunity to support research while enjoying the sport you love, Rounds 4 Research provides a way for all aspects of the game to come together to ensure its future.

After launching in July 2012, Rounds 4 Research raised more than $28,000 for turfgrass research in its pilot effort. For 2013, auctions are scheduled for June 6-16 and Aug. 1-11. You can become part of the Rounds 4 Research effort by donating a round from your facility.

If you have questions on how to participate in the Rounds 4 Research program, contact Jennifer Biehl at (765) 494-8039 or at biehlj@purdue.edu

Japanese beetle monitoring traps confirm early season in 2012

As anticipated, Japanese beetles are out early this year.  The first beetles were captured in central Indiana during the week of May 14-18. (This is nearly a month earlier than most years.)  We expect Japanese beetles to arrive in full force in this area within the next 2-3 weeks. 

Because we have never experienced such an early spring, it is difficult to predict just how the beetle populations will respond.  We know that the beetles are active early but we do not know if this means that they will be with us longer into the summer or not.  Also, keep in mind that dry conditions do not favor beetle emergence but a significant rainfall event could potentially shift emergence into overdrive.

It is safe to say that we need to prepare now, however.

Protect susceptible plants, especially those that have been recently transplanted or those that are stressed for one reason or another. Favorites host plants for Japanese beetles include linden, crab apple, plum, and other fruit trees, rose bushes, grapes, and several garden variety vegetables. 

Grub preventative applications probably cannot be applied too early this year. The newer long lasting grub control products will be a great advantage this year because we do not know exactly how long the grubs will be feeding on the turfgrass.

If dry weather continues, oviposition and grub feeding may be concentrated in irrigated turfgrass.

With all insecticides, either for adults or for grubs, it is critical to follow the label directions exactly when making applications.  

Sod webworms

Sod webworms may cause damage to closely mowed turfgrass early in the spring. Damage, similar to that depicted in the photos below, may be seen on golf tees and greens.

The overwintered caterpillars become active when the temperatures warm up in the spring and begin to tunnel and feed. They are mostly active at night, so they often elude inspection. The absence of an obvious insect makes the diagnosis difficult, - but look for patches of close-cropped turf as well as the tiny trails or tunnels in the thatch. Often the soil (and sand topdressing material) in these trails is bound together with silken material to create a cover or cap, hence the name “webworm”. Along with the damage, these tunnels help provide evidence of sod webworm activity. A soap flush is a sure method of verifying sod webworm presence.

To flush suspect areas, mix one full tablespoon of lemon scented Joy dishwashing liquid in two gallons of water and dispense the solution through a sprinkling can over 1 square meter of turf. It is best to mix the detergent into the proper amount of water by hand in order to minimize the formation of foam which can make it much more difficult to find emerging insects. Allow 10-15 minutes for the sod webworms to appear on the surface as it may take a while for the soapy water to penetrate the silk-lined tunnels these insects create.

Healthy and vigorously growing turfgrass will often ‘outgrow’ damage from sod webworms. However, if the damage is unsightly and controls are warranted, use a pesticide that is labeled for sod webworms and apply at the recommended rates. Mach 2 and Conserve are both labeled for sod webworms as well as a host of conventional insecticides. Do not irrigate after application so that the insecticide stays on the blades and in the thatch where the webworms reside and feed.
The following photo, taken two days after treatment shows the resulting dead larva.

Tim Gibb, Turfgrass Entomologist

Doug Richmond, Turfgrass Entomologist

Caterpillar Update

Although they are fairly easy to control, caterpillars like cutworms and armyworms can have a way of “sneaking” up on turf managers. For golf course superintendents, we’ve reached that point in the spring when black cutworms may be large enough to cause visible damage (»300 Degree Days). Unless you have a preventive program in place, keep an eye out for indications of damage. Black cutworm damage typically appears as small, irregularly depressed areas in tees and greens where the larger larvae have cut the grass down to the soil surface (Fig. 1)

On another note, increasing numbers of adult armyworms have been showing up in light traps around the State. These insects will lay their eggs on turfgrass leaves and stems. When they hatch, an army of hungry caterpillars will begin feeding and moving across the turf. The damage is difficult to notice at first, but as the larvae become larger (Fig. 2), they consume enormous amounts of green grass. Lawns can seemingly disappear overnight (Fig. 3). Areas that tend to be most vulnerable are those that are located next to agricultural fields, and ditches and roadways where tall grass and other vegetation is not mowed.

The following is a short list of recommended insecticides for caterpillar control (not meant to be all inclusive):

Bacillus thuringiensis Kurstaki (Small larvae only)
Beta-cyfluthrin
Bifenthrin
Chlorantraniliprole
Clothianidin
Deltamethrin
Lambda-cyhalothrin
Permethrin
Spinosad
Zeta-cypermethrin

Always read and follow label directions.

Figure 1. Black cutworm damage to a bentrgrass putting green surface. In this instance, cutworm larvae took up residence in openings caused by recent core aerification.




















Figure 2. Late instar larva of the common armyworm flushed from tall fescue turf using a disclosing solution containing 1 tablespoon of lemon Joy® dishwashing detergent in 1 gallon of water. Notice the presence of several other larvae in the background.

Figure 3. Damage to a rural Indiana lawn caused by a heavy armyworm infestation. As long as water and fertility are available, the turf will eventually recover.

Time to Water?

With the heat and dry conditions most in Indiana are experiencing, many turf areas are starting to brown. Water is critical to the growth of all plants, not just turfgrass. Turfgrass leaves and shoots are comprised of about 80% water. A lack or water (rainfall or irrigation) will lead to a decrease in growth and energy production and an increase in plant stress. When turf has insufficient water it will begin to wilt. Leaves will roll or fold to conserve water by reducing their leaf area. The easiest way to determine whether or not turf is wilting is to walk across it. If you notice that your footprints don't bounce back right away, this is a sign the plant is drought stressed. Following these initial symptoms, plants will turf from a green wilted appearance to brown in colors as the leaves die (not the plant) and the turf enters a drought induced dormancy. 

Foot-printing is the first sign of moisture stress and can be spotted when the turf does not “bounce-back” after walking across it due to moisture stress and a lack of water.

Damage from mower traffic on drought stressed turf.

Notice how the turf is laid down here after the tires from the mower ran across it and the turf has not “bounced-back” due to moisture stress and a lack of water.

How should turf be managed during dry spells and drought?

When possible stay off the turf! Limit traffic (including mowing) to minimize crushing of the turfgrass leaves and crowns and causing damage. In order to keep your lawn green during hot and dry periods at least 1.0 inch of water will need to be applied weekly. However, with far less water you can keep your lawn alive. Water once every 2-4 weeks with ½ inch of water to keep turf plant crowns hydrated during drought. This amount of water will not green up the turf, but it will increase its long-term survival during long dry spells.

When irrigating it is best to irrigate early in the morning, but occasional watering at mid-day or early in the morning in order to prevent injury from moisture stress is allowable. Following wilt, turf should recover very quickly within a few hours. However, following drought (brown turf), turf will require at least 1-2 weeks after significant rainfall returns to recover.

Aaron Patton, Turfgrass Extension Specialist

Guess Who Came to Dinner?

The photos below were submitted to our laboratory for identification.  While there are no animals present in the photos, the damage depicts the problem very nicely.

Even without seeing any, I am quite certain that the turf is infested with white grubs. 

As you know, white grubs do some damage to grasses, but what damage they cause is sometimes more than compounded by other animals coming in to forage for the grubs. 

Such is the case with this incident.  It is clear that either raccoons, skunks or opossums have been digging for grubs in this area.  The turfgrass ripped up and strewn all around (Photo #1) is evidence of foraging by these animals.

The second photo of ‘peck holes’ is similar evidence of grub foraging but in this case it is caused by birds.  Apparently, they also are enjoying the grub buffet.

Together, these photos show the result of what may have been somewhat tolerable grub injury to a lawn, made intolerable by animal foraging on the grubs.

Since the grass is pretty much dead at this point, the only solution is to rake it up and replant or lay sod.  Laying sod gives a quick fix to the problem, but not all animal foraging damage is this severe.  Keep in mind that any grass that is not torn up will survive and thus give a head-start to an over-seeding strategy.

Consider applying grub control treatments during late July or August to prevent grubs from re-occurring next year.

Grub foraging damage by mammals

Bird peck-holes 

Tim Gibb

 Insect Diagnostician

 

Japanese Beetle Emergence Begins

We captured the first Japanese beetle adults of the year last week in our traps on the Purdue Campus. These traps are located in an area where emergence tends to take place much earlier than at most locations, so don’t expect to see any significant wide-scale emergence for another 2-3 weeks. We monitor this particular site in order to be able to provide turf and landscape managers with an early heads-up so they can prepare as necessary. For turfgrass managers concerned about controlling the larvae (white grubs) of this insect, the chart below provides guidance on product selection and timing in relation to expected efficacy.

Doug Richmond

Turfgrass Entomologist

Educational Opportunity:

Turf Field Day
Tuesday, July 19, 2011
Daniel Turf Center, West Lafayette, IN
Attendee Registration Form
Exhibitor Registration Form

Grassy Weeds in Turf Planted Last Fall

Many samples have arrived in the Plant and Pest Diagnostic Lab the past few weeks with the common question of “What’s this grass in the turf I seeded last fall?”. Although there could be a host of answer to this question with annual bluegrass likely on the top of the list, most of what I have identified is either annual ryegrass or winter wheat. Annual ryegrass is a common ingredient in poor quality seed mixtures and winter wheat is commonly found in areas planted with wheat straw as a mulch. Both species should die during the warmer summer months without the need to apply a herbicide. Below are some pictures and helpful clues for identifying these grasses in turf that you plant.

 

 

 

 

 

 

Aaron Patton, Turfgrass Extension Specialist

Don’t Forget to Sharpen Those Mower Blades

Sharply cut leaf blades increase turf health by improving recovery, decreasing water loss, and increasing photosynthesis. Lawns mown with a dull mower blade have poor aesthetics, heal more slowly and have greater water loss. Seedheads are present in many lawns right now and they are typically tougher to cut than the grass blades themselves. As such, it might help to switch to a sharp set of mower blades to help slice through these seedheads.

Homeowners should sharpen mower blades at least twice a year. To make this easy, buy two sets of mower blades and sharpen both sets each winter. Put a sharpened blade on before the first mowing and then switch when you notice that the leaf blades are becoming ragged in appearance as this is an indicator of a dull mower blade.

For professionals, consider sharpening mower blades weekly, bimonthly, or monthly depending on the amount of turf you are cutting. Again, inspecting the turf leaf blade is the best way to determine when your mower becomes dull.

Aaron Patton, Turfgrass Extension Specialist

Spring Diseases in the Midwest

Spring has finally arrived and it is accompanied by the usual compliment of infectious turf diseases.  There should be no confusion between two “rhizoctonia” diseases.  Yellow patch (aka cool season brown patch) prevails during early spring, when rainy weather is combined with cool nights.  It also affects al turf species and the circular patches are most prominent on shorter mown turf (putting greens and surrounds).  Brown ring patch (aka Waitea patch) visits later in the spring evening temperature increases.  It is largely restricted to annual bluegrass.

Melting out on perennial ryegrass and Kentucky bluegrass is flourishing in some stands of taller mown turf (golf course roughs, municipal athletic fields and residential turf).  Red thread and pink patch are bloom, and the solar spot pathogen has awakened and will make its presence known shortly (in my opinion).   

Here in West Lafayette, soil temperature has increased to the point where the summer patch pathogen is emerging from dormancy.  Our soil temperature monitor suggests that we are entering a period when applications of effective fungicides may limit infection.

For more information, including color images of these and other infectious diseases of turf, go to our Purdue Turf Program Website (www.agry.purdue.edu/turf/). 

For more information on weather and turf diseases, go to http://btny.agriculture.purdue.edu/turfcast/

Rick Latin
Turfgrass Pathologist

TURFCAST

If you are interested in periodic assessments of turf disease threats in Indiana, then you should check out our TURFCAST website. The website offers daily risk assessments for certain diseases (dollar spot, brown patch, and Pythium blight) and weekly comments by me at "Turf Disease Watch" this is based on my observations at Purdue¹s Daniel Turf Center and out in the state. It also includes a chart of soil temperatures recorded here in West Lafayette, which I use to comment on the timing for fungicide applications for summer patch control.

You can access TURFCAST through our Purdue Turf website (www.agry.purdue.edu/turf/), or simply Google "Purdue TURFCAST".

Rick Latin, Turfgrass Pathologist

Flooding on turf

April was a wet month in Indiana with rainfall totaling 2-10 inches more than normal in April for areas of Indiana (see precipitation map below). Heavy rainfall can cause flooding stress on turf. Flooding reduces oxygen to the plants from the soil and could ultimately lead to plant death without oxygen. If water saturation is only around the roots in the soil while shoots (leaves) are exposed to air, the damage to turf is much less than when plants are submerged under water. In addition, soil erosion and deposition, debris, and the accumulation of toxic substances can also kill turf following flooding events.

Plant survival depends on several factors: turfgrass species, submergence depth and duration, and water temperatures. When submersion occurs simultaneously with high temperatures, plants can die quickly due to a lack of the energy production to sustain plant growth. Plant survival can be either through fast growth to above the water to obtain oxygen or slow growth to reduce carbohydrate consumption. For common turf species, creeping bentgrass and bermudagrass are most tolerant of flooding. Kentucky bluegrass and tall fescue are fairly tolerant. Annual bluegrass, perennial ryegrass, and red fescue are least tolerant.

Turf discoloration and yellowing is a common symptom of flooding stress due to loss of chlorophyll and nitrogen uptake. Once water has receded, a light fertilizer application will help grass recovery. Soil cultivation improves the physical condition of soil and increases oxygen concentration to the roots, which will benefit the regrowth of the turf. Walk-mowing with lightweight equipment in moist or saturated soils will help reduce soil structure damage compared to heavier ride-on equipment.

Yiwei Jiang, Turfgrass Physiologist

Assessing Spring Freeze Injury in the Landscape

As most gardeners have marveled, we're having one of the earliest "spring" seasons this year, with woody plants and herbaceous perennials three to six weeks ahead of "normal."

And then, perhaps inevitably, "normal" spring frost and freeze visited. Being so much further along in their development, plants are quite vulnerable to damage.

 

Home fruit-growers have reason to be concerned: At 28 F, you can expect a 10-percent loss of flowers/young developing fruit. However, at 25 F that loss increases to 90 percent! Here, in the Lafayette area, we hit 27-28 F last Thursday (April 12) morning, followed by 24-25 F Friday (April 13) morning - a double whammy.

Bud counts were exceptionally high until the freeze, so in some cases, even just 10 percent retained fruit might still be a decent crop on our tree fruits. Grapes may also still have ability to crop on shoots that have yet to emerge. Strawberries are a bit easier to protect through frost and freeze, but only if you took measures, such as using floating row covers, recovering with straw, etc.

However, it is only mid April, and additional frosts/freezes are still possible. Bottom line is that unless it is already a complete loss, we won't really know the rest of the story for quite a few more weeks. 
It is easy to check fruit buds for damage by cutting open the bud and looking for dark brown or black centers. Our Purdue Extension fruit specialists put together these videos to help you assess the status of your fruit plants.

Assessing Spring Freeze Damage to Apples
Video: http://youtu.be/YcSRg74Hb_A
Assessing Spring Freeze Damage to Peaches
Video: http://youtu.be/DcS2XGAqoFk
Assessing Spring Freeze Damage to Grapes
Video: http://youtu.be/lNUZu5Bx08M
Assessing Spring Freeze Damage to Strawberries
Video: http://youtu.be/F-QoX1C4_S0
Assessing Spring Freeze Damage to Blackberries
Video: http://youtu.be/EyIhvfY2apM

For ornamental trees and shrubs, plant response has been quite varied, depending on species, location and, of course, temperature and duration of that temperature. Susceptible plants may have wilted leaves, brown or black necrotic spots on leaves, or perhaps dieback of entire twigs. Plants that were in bloom likely have brown petals or dropped flowers entirely. Here are some links to articles from previous spring freezes that will give more information.
http://www.ppdl.purdue.edu/ppdl/hot10/5-14.html
http://www.ppdl.purdue.edu/ppdl/weeklypics/Weekly_Picture6-25-01-1.html





Note that freeze incidents are normal for this time of year. What is abnormal is the earliness of development, leaving the plants exceptionally vulnerable to freeze. The good news is that woody plants, in most cases, will outgrow the damage.

B. Rosie Lerner, Purdue Extension Consumer Horticulturist

Article originally posted at: http://www.agriculture.purdue.edu/agcomm/newscolumns/archives/YGnews/2012/April/120419YG.html