Weeds
Asiatic Hawksbeard
Q: What is the weed that has big leaves at the bottom;
puts up a thin stalk
with
a cluster of little yellow flowers at the top? It is not a
dandelion. I see it every where now.
A: I believe you are describing Asiatic Hawksbeard, Youngia japonica. This is classified as a cool season annual although it has been known to survive our winters. It’s only means of reproduction is by seed so if you can pull it up before it produces a flower or use a weedeater, this weed is not too difficult to control. It is common in Florida, found as far north as Pennsylvania and west to Louisiana. It is a native of Southeast Asia.
Black Medic
Q: What is this horrible clover-like weed I am seeing everywhere, including my lawn. The flower is a round, yellow cluster. It runs similar to crabgrass but I think the leaves look like clover. My wife says it is not clover, but I think it is. We have a bet on this; the loser has to clean the kitchen for a week. So you get to decide - what is it?
A: I always hate to get into the middle of a husband and wife disagreement especially when cleaning the kitchen is the bet.
So, I will have to agree with you that the leaves are similar to clover but your wife is correct in that it is not clover. The weed you brought to the office is Black medic, Medicago lupulina. The name sounds ominous does it not? This plant originated from the Mediterranean. It has traditionally been used as a winter annual crop cover in the United States for corn, soybeans and small grains. This is the best time to get rid of the weed as the black seed clusters are now maturing. It is fairly easy to pull which is the best method of control, since it is an annual, and reproduces only by seed. Once the plant and seeds are removed then next years crop will be greatly diminished. Any chemical weed killer will be of little benefit as these are currently fully grown adult plants. The time to apply a chemical is when the weed is very small and before it has reached reproductive stages. This weed grows in the same type of environment as clover and they are often seen together. One other important fact, black medic can be an indication the lawn has too little nitrogen.
Beggarweed
Q I would like to know the scientific name of beggerweed which has 3 leaves, a purple flower and grows about 8 inches tall and how to control it.
A: I believe you are referring to the weed commonly
called 
Creeping
Beggarweed whose scientific name is Desmodium incanum. It
is found throughout Florida, Texas, Mexico and countries further
south. As a child, I remember spending many a day picking the Creeping
Beggarweed seeds off my socks and the fur of my family pets. I always
got the fun jobs when I was young. This is a perennial weed with
a large taproot and many long extensively branched runners which
roots at the nodes. The leaves contain 3 leaflets which vary in size
but are generally elliptical and hairy. The stem is erect; flowers
range in color from pink to deep rose but are often small and inconspicuous.
The fruit forms with six or eight rounded segments which when ripened
break off easily and attach to clothing and animal fur. Reproduction
can occur by seed, stolons, and broken taproots. It is often found
in turfgrass, open woods and disturbed areas. Use an herbicide for
broadleaf weeds, but be careful to read the label and follow instructions.
It is important the find an herbicide that will not damage your lawn
grass.
Q: We have an infestation of a weed (creeping beggarweed?), which has spread to the extent that removing by hand from the centipede grass is not an option. Do you have any suggestions as how it may be treated?
A: You are correct; this weed is probably creeping beggerweed, Desmodium incanum. It is a perennial with a large taproot. Its leaves are in groups of three and the flowers are light pink to rose. It reproduces by seed, stolons and broken taproots so you need to use great effort to completely remove the root if you decide to dig it up. You could use a pre-emergent next spring to help control it. It is at the reproductive stage now and will be difficult to control with typical weed killers. One other thing, if you can locate the main stem, cut it close to the ground and immediately “paint” the cut stem with a Round-up type product. Don't spray this chemical as it could easily drift to your grass and kill it. Use a craft sponge paint brush, dipped in the chemical then apply it exactly where you want it to go. This weed is common throughout Florida and Texas.
Burweed
Q: What can you tell me about burweed?
A: Burweed is also known as Carpet burweed or lawn burweed from the genus Soliva. 
You mentioned being stuck when you tried to pull it up. There is a small spine on the end of each of the seeds which is able to piece the skin and can be painful. Burweed is a cool season annual and it has only one way to reproduce – by seed. The good news is this weed is an annual which means if you pull it before the seeds fall to the ground you have killed any future plants. We would suggest you remove the weeds by using a hoe rather than hand pulling. Pre-emergent herbicides do not work well on this weed as competitors are wiped out allowing the burweed to thrive. .
Chamberbitter
Q: I have a weed that appears to be taking over my St. Augustine lawn. It seems to be born bearing seeds. Can you tell me what it is? Plus I was told to add lime to my yard to get control my weeds. Will that really work?
A: The weed you brought to my office is called
Chamberbitter (Phyllanthus urinaria L.) .
You
described it accurately when you said is is born with seeds. If
you check under the stems you will locate dozens of seeds. It
is classified as a summer annual and is found throughout Alabama,
Georgia, Florida and Texas. It is native to Asia and found
commonly in the tropics. I obtain a great deal of personal
satisfaction from pulling these out by hand to ensure the seeds will
be destroyed. Regarding adding lime to control the weeds, we
have no evidence this practice does anything to control weeds. Lime
is added to raise the soil pH and I would only advise you to add
lime if a soil analysis indicated a true need. Once lime is
added and the soil pH is raised, it is very difficult to adjust or
lower the pH. The pH is an indicator of your soil acidity and determines
how nutrients are absorbed through the root system to the plant. If
the pH is too high or too low your grass can develop problems. Most
St. Augustine grass prefers a pH of 6.5 so we will need to test your
soil before we decide on the next course of action. Remember
to take care of your grass by mowing grass at highest height,
water only as needed, fertilize with 15-0-15 or 16-4-8 two to
four times a year, and avoid using weed and feed products.
Cutleaf Evening Primrose
Q: Please identify this weed for me.
A: I appreciate you bringing in a sample of the plant. It
is difficult to identify plants and
insects without having a good
sample. Often flowering plants are classified as wildflowers
or weeds depending on where they are growing. By definition,
any plant out of place is considered a weed. Anyway, I said
all that to let you know some people call your plant, Cutleaf Eveningprimrose, Oenothera
laciniata Hill, a weed and others call it a wildflower. This
is an herbaceous plant which can reach up to 2 feet tall and have
a much larger spread. The leaves are heavily toothed and arranged
alternately on the stems. The flowers have four petals with
a combined span just over inch. They are pale yellow sometimes pink.
Blooms first appear in late spring and continue into early fall.
Cutleaf Eveningprimrose is found in fields, fencerows and disturbed
areas. This simple plant can be found in almost all of North America
east of the Rocky Mountains and some areas west of the Rockies. Managing
it will be difficult now that it is fully developed. Most herbicides
work best when the weed is young (1 inch or smaller). You could
apply a non-selective herbicide. But, be careful not to spray
the product around other green plants as they will suffer the consequences
(death!). Or you could just leave it alone and call it a wildflower!
Dichondra
Q: I have this weed in my yard that looks similar to dollarweed but I know it is different. Can you tell me what it is?
A: It was easy to identify this weed once you brought me in a sample. Dichondra or Ponyfoot, Dichondra carolinensis, is a perennial plant that reproduces by seed and stolon. In some areas of the country dichondra is used as a popular ground cover in place of grass. Once established it grows just as well in full sun as shade. It is not salt or cold tolerant and does not respond well to foot traffic or compacted soil. Dichondra is often found living underneath the canopy of trees as it is protected from severe cold by the tree branches. This plant requires quite a bit of water and nitrogen to maintain good health. I suspect you may be applying too much of both to your lawn, which is a common practice in Northeast Florida. St. Augustinegrass grown in our area will often become stressed and weak after a few years of over fertilization and over watering. This poor management practice often results in weeds growing heartily in the lawn’s place. Remember to use 15-0-15 fertilizers on St. Augustingrass with at least 25% of the nitrogen in a slow release form during the months of March, May and September. Use iron sulfate during the summer with as little nitrogen as possible. It is best to water St. Augustinegrass on an “as needed” basis. Water when the grass blade starts to slightly fold onto itself, which means you should set your irrigation system on manual. Ideally, you should only water between the hours of 6am – 10am. Keep your St. Augustinegrass at 3.5 – 4 inches high and never remove more than 1/3 of the blade at any mowing. Never scalp or cut the lawn extremely short. It is not advisable to add lime to the yard unless a soil analysis advises you to do so. So how do you get rid of dichondra – maintain a healthy lawn by using best management practices of proper fertilization, irrigation and mowing.
Doveweed
Q: What the heck is this weed growing in my St. Augustinegrass?
A: I am glad you brought this weed into the
office for me to identify because it is so similar 
looking
to grass. The weed you brought in is Doveweed, Murdannia
nudiflora (L.) Brenan or Aneliema nudiflorum (L.) Kunth. It
is classified as an annual grass-like weed which makes it difficult
to kill because it is a distant relative of turfgrasses such as St.
Augustine. It loves moist areas and tolerates shade very well. Doveweed
produces attractive, small purple or blue flowers but they are not
very showy. The good news is that is reproduces by seed only,
which means you should use an herbicide (pre-emergent) that will
discourage the seeds from germinating next year. Pre-emergents,
such as atrazine, should be used only twice a year (once in the spring
and once in the fall). This product is very potent and the
label must be followed to avoid environmental damage. Keep
it away from water areas such as retention ponds and wells. Nothing
will kill the adult, seed producing plant now except a non-selective
herbicide like Round-up. Of course, if you use a non-selective
herbicide you run the risk of killing any green plant it touches.
You might consider pulling this weed since it is an annual. The
upside to pulling is you get rid of the adult and the future offspring
all in one fell swoop.
Q: I have a terrible problem of doveweeds! My yard guy sprayed a pre-emergent, but they still seem to be spreading. What should I do?
A: The bad news is doveweed is an annual, which means is produces huge numbers of seed. The good news is doveweed has no other way to reproduce except by seed. Therefore, the best management of the weed is to get rid of it before it produces seed. I know it is tedious but hand pulling is one of the best ways to control annuals combined with the pre-emergent your landscape maintenance professional applies. Late summer is not the best time of year to apply weed killers, which the weeds apparently know because this it the peak time of year for weed production. The only way to kill the adult weed during the summer is to use a non-selective weed killer, which will harm the grass or ornamental you are trying to save. Consider giving your landscape maintenance professional another year to get the weeds under control by putting out an application of a pre-emergent in the fall of 2008 and spring of 2009. These applications do not kill the adult weeds but they help prevent the seeds from germinating the following season. Be patient – this is the best way to manage the little pests. In addition, be sure you are putting your energy in caring for the lawn properly by mowing, watering and fertilizing using the appropriate amounts.
Florida Betony
Q: What is this weed growing in my yard? I brought in some fill dirt from an area in the woods and now I have a weed I cannot kill.
A: What you have is called Florida Betony, Stachys
floridana, or Rattlesnake weed. 
The name for the genus, Stachys,
is derived from the Greek word stachys, which means an
ear of wheat or spike, as the flowers appear to be arranged in
a similar way. The Latinized English species name floridana refers
to the fact that it was first named from a Florida collection.
This species was thought to be restricted (endemic) to Florida
until the 1940s or 1950s. However, it is now found as far west
as Texas and as far north as Virginia. The stems of Florida
betony are hairy, square and upright, and grow to between one and
two feet tall. It leaves looks similar to the mint family and spreads
just as quickly. The trumpet-shaped flowers are
white to pink and may have purple spots. The underground tuber is
the reason for the common name "rattlesnake weed". It
is segmented and white and resembles the rattle of a rattlesnake.
Florida betony will grow in full sun to part shade and tolerates
a wide variety of soil conditions including wet or dry. Florida
betony reproduces primarily from tubers but also from seed and
rhizomes. Throughout the winter months, it will grow and spread
rapidly, especially in the loosened soil of landscape beds. If
you are finding Florida Betony in the lawngrass your best management
is to maintain a healthy, dense lawn by fertilizing, watering and
mowing at the proper height and frequency. If it is growing in
flower beds, remove as much of the root as possible, but small
amounts of non-selective herbicide may be required for best management. It
is aggressive and will take over an area if not kept in check.
Globe Sedge
Q: I have this weed all over my yard. Is it going to become sandspurs?
A: The weed you brought into the office is called Globe sedge Cyperus
globulosus Aublet.
It is a perennial weed of turf found
in moist and sandy habitats. The seedhead is comprised of several
spikelets. Each spikelet consists of a long stalk with a round
cluster of seeds perched on the end. Cylindric sedge and globe
sedge seedheads are very similar in appearance. However, globe
sedge seedheads are round, whereas cylindric sedge seedheads are
oblong.It will never become a sandspur so you needn’t worry
about that problem. It can tolerate any kind of soil conditions
from sandy to bog-like. It prefers some shade especially in
the afternoon. Globe sedge is difficult to control it once
it matures to reproductive age. You can manage it now by using
a non-selective herbicide. Consider applying a pre-emergent
herbicide in the early spring of next year to better control this
weed. In addition, be sure you are irrigating your lawn appropriately. St.
Augustinegrass prefers to be watered deeply but less often in order
to build strong deep roots. Consider applying ¾ to
1 inch every time you irrigate, which ideally should be once every
5-7 days. Watch the grass blade. If it is full and green,
it does not need to be watered. It would be a good idea to add
a rain sensor to your in-ground irrigation system. A rain
sensor will prevent your irrigation system from going on if we
have received sufficient rain.
Japanese Clover
Q: Can you identify the weed that is all over my yard?
A: The weed you brought to the office is called Japanese
clover, Lespedeza striata, or Common Lespedeza. 
It
is a prostrate, freely-branched summer annual. The leaves are
very tiny and they form a dense mat. Japanese clover produces
small purple or pink flowers, which are actually quite striking up
close but the plant is basically too small to have much ornamental
value. Flowering occurs during July – October and it
reproduces by seed only. Common Lespedeza can found in fields,
pastures, open woods, stream banks, roadsides, railroads, waste ground,
disturbed and cultivated sites. This plant is utilized for horse
and cattle forage. It was brought to this country around 1904
and has spread rapidly. It is difficult to kill a mature, seed
producing plant once it has reached its maturity. When I say
maturity I mean it has reached the stage of its life cycle where
it is capable of producing seed. You might consider pulling
it up prior to it releasing seeds and/or use a pre-emergent herbicide
next spring to possibly prevent the dormant seeds from germinating. Of
course, our major focus should be taking care of the lawn so it is
strong by proper fertilization, watering and mowing. Check
out the University of Florida website on residential St. Augustinegrass, http://edis.ifas.ufl.edu/LH010
Japanese Stiltgrass
Q: What is this weed growing in my yard?
A: I
believe the specimen you brought into the office is called Annual
Jewgrass or Japanese Stiltgrass, Microstegium
vimineum. This warm season annual grass can be creeping
or erect. The good news: it reproduces only by seed. The
bad news: it is difficult to manage and control in St. Augustinegrass
since they are both grasses. It prefers moist, shady areas
which would keep the St. Augustinegrass thin and allow Japanese
Stiltgrass to become better established. Your best plan of action
now is to dig up what you can before it produces a seed head. You
could dab small amounts of glyphosate (Round-up) on the leaves
(do not spray) and it will die within the week. If this weed
is too widespread then you must be diligent to spray a pre-emergent
next summer to prevent the weed seeds from germinating.
Q: What is this grassy weed in my lawngrass?
A: Once you brought in a clump of the weed into the office it was easy to identify. I have received two other such inquiries about the same weed, so it was fresh in my mind. Annual Jewgrass, Microstegium vimineum, is a summer annual which prefers shaded areas. It goes by other common names such as: Japanese grass, Japanese stiltgrass. Nepalese browntop and Nepalgrass. It is considered a noxious weed in Connecticut, Alabama and Massachusetts. This weed is native to Asia and found in the United States from Ohio to Virginia southward. It has no means of reproduction aside from seeds and this limitation makes it easier to control than perennial weeds. Use a hoe, rake or remove by hand before it produces seeds then your chance of having this weed next year are greatly diminished. Summer is not the best time of year to apply weed killer to lawn grasses as the herbicide may weaken or even kill the grass you wish to keep. A pre-emergent herbicide could be used next spring to reduce the seed germination of this weed.
Matchweed
Q: Can you identify this weed I am finding in my lawn and how do I get rid of it?
A: Thanks for bringing this weed to the office
because describing it over the phone 
makes
it difficult to identify. The weed is commonly called Match
Head or Matchweed, Phyla nodiflora. It is a mat-forming
perennial which reproduces by seed and stolons. It is a common
weed which is found from Pennsylvania south to Florida and as far
west as California (even Hawaii). This is not the best time
of year to use any type of broadcast weed killer on the lawn as it
may damage the lawn too. I suggest you consider applying a
Round-up type product but do not spray it on the weeds as it may
drift to other parts of your lawn and kill it. It would be
better to use a craft sponge paint brush dipped in the pre-mixed
glyphosate product and paint it directly on the weed leaves. Be
sure the sponge is not dripping to avoid the herbicide falling on
plants or grass you do not want killed. These sponges can be
found in the paint section or craft center of your local hardware
or department store.
Mushrooms
Q: My grass is newly sodded and with the recent rains I have noticed small, beige mushrooms growing in the grass. Should I do anything about them?
A: Often turfgrass is grown in heavy organic matter. As you have seen the mushrooms will pop up when rain fall is abundant or irrigation is increased in order to get the turfgrass established. The best method of control is to remove the mushrooms as soon as you see them. Place them in a plastic bag and throw them away. Try to harvest them before they completely open to avoid the spread of mushroom spores. Don’t get discouraged, you can eventually remove this mushroom by persistent hand picking. By the way, this method works for any mushroom even those you find in your mulch.
Oxalis
Q: I am not sure what I have in my lawn, but it is taking over and nothing is helping to get rid of it. The leaves are similar to clover. It has a root that looks like a white radish and blooms are purple. It has spread all over and is in large clumps choking out my grass. I pull all I can each year, but it is more than I can handle now. I live in Fernandina Beach. Hope you can help.
A: The weed you have is in the family oxalis, which
if placed in a pot is often called shamrock.
The
flowers may be white, purple or yellow. The petals often resemble
clover which causes people to confuse this plant with a common variety
of clover. This particular lawn weed is difficult to control because
it is classified as a perennial. Unlike annual weeds, which only
reproduce by seed, perennials can reproduce by seed and vegetatively
using other parts of the plant like the root, stolen or leaf. Pulling
weeds by hand, which is my favorite pastime, often is unsuccessful
with perennials because of their ability to reproduce in a variety
of methods. Any portion of the weed left in the ground can produce
a new plant, hence the reason why some weeds seem to be so stubborn
and continue to return year after year. You will need to be persistent
with this weed and consider using a weed killer for broadleaf weeds
but be sure the product can be used on your type of grass. In addition,
you should spot treat only the areas where the weeds exist, avoid
spreading the product over the whole lawn. One other thing to consider
is why weeds are coming up in your lawn. Healthy turfgrass should
allow few weeds the opportunity to grow. If your turfgrass is St.
Augustine remember to water it once every 5-7 days in the summer
and once every 10-14 days in the winter. Water the lawn in the morning
hours between 6am and 10am. Use a fertilizer product similar to 15-0-15.
Look closely at the label and try to find a fertilizer product that
has a portion of the nitrogen as slow release nitrogen. The first
and last numbers on the label, which stand for nitrogen and potassium,
should be balanced meaning the ratio should be 1:1 or at the most
2:1. Mow the lawn at the highest height. Fertilize in March and August
or September. Avoid using weed and feed products. Use an iron sulfate
product that contains only small amounts of nitrogen during the summer
months.
Sandburs
Q: How do I get rid of sandburs in my yard?
A: I have received many questions this month
about getting rid of weeds
but
the main problem has been the maturity of these weeds. It is
very difficult to kill adult, seed producing weeds in lawns. The
time for treating weeds is when the plant is very small, when it
is easier to manage. We have very few chemicals in our arsenal
that will kill mature, reproductive weeds. Ideally, we should
be taking care of our lawns to reduce the number of weeds. Proper
care of lawns means strong healthy, nearly weed free lawns. First,
we should fertilize using 15-0-15, Nitrogen, Phosphorous, Potassium,
respectively. I know as Americans we feel if 15% Nitrogen is
good, then 30% or 50% would be better – not necessarily. Balance
in everything, including lawn fertilizers. Fertilization should occur
in March, May and September but NEVER in the summer months. Irrigation
is also essential in maintaining a healthy lawn. Water lawns
6-10am about ¾ to 1 inch of water. You will need to
measure your sprinkler output. Put out empty cat food or tuna
fish cans (10-15) at a zone and run your system. After 20 minutes,
stick a ruler in the cans and measure your system’s output. Run
your sprinkler system until it reaches the ¾ to 1 inch so
you know how long you need to water your lawn. Do not add lime
to the yard unless a soil test dictates the need for lime. Now
to get back to the sandbur problem; you could use a product called
IMAGE but it must not be used in cold or hot weather and there are
several don’t when using this product so please read and follow
label directions. But the best advice I can give you is to
get rid of the seed heads (the stickers) on the weeds and apply a
pre-emergent herbicide next year to prevent the seeds from germinating.
Skunk Vine
Q: What is the name of the vine-like weed
growing in my turfgrass? They are not difficult to pull up
but it does smell unpleasant when it is disturbed. I have
never seen it flower.
A: After bringing me this specimen, it was easy to identify as skunk vine mostly because of the strong, unpleasant odor. The plants are woody vines but it lacks thorns. It does produce small, pale lilac flowers but they are so small they may not be conspicuous to you. After it flowers it produces small, yellow-orange fruits. Skunk vine and sewer vine are easily separated from one another by their fruits. Skunk vine has spherical fruits and the seed (diaspores) lack wings, whereas sewer vine has fruits that are laterally compressed and seeds that are conspicuously winged. The leaves of sewer vine are typically larger than those of skunk vine. The common English names of these plants relates to the odor of the leaves, which is due to the presence of sulfur compounds (Mabberley, 1997). The odor is another helpful characteristic used to identify these vines and it sets them from other plants. For those of you who are literalists, I don’t think it really smells like skunk but it is nonetheless disagreeable. In urban landscapes, this vine entwines branches of woody ornamental plants and also spreads horizontally through lawns, rooting at the nodes. Skunk vine is a Category I Florida Exotic Pest Plant Council weed (Langeland and Craddock Burks, 1998), a listing that groups the plant with the most invasive weed species in Florida .
Sow Thistle
Q: Last year I had mulch delivered and now there are dozens of these tall weeds with yellow flowers. My gardener has been pulling them up by the handfuls. Can you tell me what they are?
A: I believe the weeds you brought to the office are sow thistles. They are very tall with yellow flowers. The perennial sow thistle is less spiny with a larger taproot than its annual cousin. These are common lawn and landscape weeds found throughout most of the United States and Canada. After the flower is spend it produces white, fluffy seeds that can easily be carried on the wind to other areas of your yard or even your neighbors’ yard. Pulling them up now to get rid of the flower before it produces seed is a good strategy. You might consider having your gardener put out a pre-emergent herbicide (providing he has the appropriate pesticide license) in the fall. This will help prevent any seeds from germinating during the cooler winter and early spring seasons.
Weed Cloth
Q: My husband and I are disagreeing about whether to add weed cloth to my tree and shrub beds. What do you think?
A: Well, first I am glad you did not tell me which side you were on, that makes it easier for me to answer your question without prejudice and I sure hope no money was riding on this. Weed cloth does a fair job of keeping out weeds, but only a fair job. The real “bad boy” perennial weeds such as nutsedge, Florida Betony and dollarweed are able to eventually find their way through this stuff. The true weakness of this product is in what it doesn’t do. It does not allow fertilizer to reach the root area effectively, which is where it needs to be applied. It has a tendency to compact the underlying soil, which can be a real problem for trees and shrubs that need oxygen to develop strong roots. Mulch is generally added on top of the weed cloth, which can compound the soil compaction problem. In addition, weed cloth does not allow for the enrichment of soil if you add organic matter or use natural mulch such as pine straw or oak leaves. So, the best answer is to use natural yard wastes such as leaf debris, pine straw, and grass clippings in your shrub and tree beds. If a weed pops up, pull it or paint it with an herbicide that contains glyphosate (Round-up) – don’t spray it. If you spray Round-up the herbicide can drift to other plants you want to keep. Then take the money you would have spent on weed cloth and buy another plant.
Weeds
Q: I have sedges and dollarweed growing all over my yard. In fact, I have very little St. Augustinegrass left. What can I do?
A: Sedges and dollarweed are what we call indicator weeds, which means they can tell us something about the soil conditions of your yard. These two weeds in particular tell us the area is wet or poorly drained. You may consider trenching the area to allow water to drain better. If drainage is not the problem then consider adjusting the amount of water you are putting on the lawn. Ideally, you should let the grass tell you when to water. If the blades of grass are fully open then watering is not necessary. Water lawn grass once the blades begin to fold. Irrigate in morning hours only (6-10am). Water the lawn about once every 5-7 days in the summer and once every 10-14 days in the winter. Irrigate ¾ to 1 inch each time as the grass responds best to deep watering. Control is going to be difficult once dollarweed is well established; but management should include an application of an herbicide in the spring and fall only. However, chemical applications must be coupled with watering and fertilizing properly. Avoid high nitrogen fertilizers and weed/feed products. Fertilize in March, May and September only using a slow release fertilizer such as 15-0-15.
Q: I have weeds coming up in my lawn. What are they and how can I get rid of them?
A: This question has been coming into the office in large numbers. The type of weed varies but most have been summer annuals such as Chamberbitter or crabgrass. Summer is not the time of year to ut out weed killers as they may do more damage to the lawn than the weeds. If possible, hand pull the annuals before they produce seeds, which will stay in the ground until next summer. By hand pulling the weeds, you not only get rid of the adult plant now but also next year’s plant. If the weeds are in one main area you can paint them with a non-selective herbicide (like Round-up) and it will kill the weed. However, you must be careful not to spray or drip the product on any thing except the weed.
Q: Even though it is winter I have two types of weeds in my lawn which seem to be thriving. One of the weeds has small white flowers on it and the other looks like clover with small yellow flowers. What kind of weeds are these?
A : It is difficult to determine the identity of
plants over the phone, 
but
after seeing these weeds the mystery became easy. Both are very common
broad-leafed weeds and as you noted grow very well in the winter.
Common chickweed, Stellaria media, is the one that produces
the white flower. It is a mat-forming winter annual that reproduces
by seed and is found throughout North America except for the Rocky
Mountains. The other weed is called Yellow Woodsorrel, Oxalis
stricta, which is a perennial. It is found in most of the eastern
and central United States and reproduces by seed. Yellow Woodsorrel
or Oxalis comes in a creeping and upright form; it also has attractive
heart-shaped leaves which look similar to clover.
Q: While applying a weed killer (herbicide) to my lawn, some of the weed killer got around the roots of my shrubs and now portions of the shrubs are damaged. What can I apply to correct the damage? Would it help to put out some fertilizer?
A: Once the shrub is damaged by an herbicide or weed killer, the damage is permanent. It doesn’t mean the shrub will completely die, only the portions damaged. Applying fertilizer now, I believe, would complicate the problem because fertilizing the shrub would encourage new sprout and stem growth which would be exceptionally tender should we experience a cold snap or drastic drops in temperatures. It is best to keep the plant watered properly then take a “wait and see” attitude. Hopefully by next spring any new growth will cover the branches and foliage lost this year to the herbicide. You can remove any of the dead branches now if you like, but other than that, let the plant do its best to recover on its own. If you were using a broadcast spreader to apply your herbicide, consider purchasing a shield to limit the broadcast area. In the future you may want to avoid applying herbicides near the flower, tree and shrub areas.
Yellow Nut Sedge
Q: I have a weed in my yard that looks like fine grass, but I when I dig it up the root it has a small, round ball attached to it. It is so aggressive that it even pops up through the weed cloth I have put down in my flower beds. What is this weed?
A: Probably what you have is a yellow nut sedge and
you are correct in 
stating
it is aggressive. It is a rapidly spreading perennial that puts out
a long stem and a yellow-brown seed head. Stems of sedges are triangular
(“sedges have edges”) whereas grass stems are hollow
and round. It reproduces mainly by tubers and is found throughout
the United States. Several herbicides can temporarily suppress yellow
nutsedge populations; however, eradication of established nutsedge
in lawn grass is extremely difficult. Some herbicides kill the yellow
nutsedge plant tissue, however new plants can emerge from the tubers
in the soil. Although it looks similar to grass the leaves of sedges
are thicker and stiffer than most grasses. In addition, yellow nutsedge
is a lighter yellow green color than St. Augustine grass. Sedges
in general prefer moist soils so their presence may be an indication
of too much water or the area is lower than the rest of your landscape.
If over watering is contributing to the problem, reducing the amount
of water may be beneficial.