Horticulture August 2023 Newsletter
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Brown Patch Disease in Kentucky Lawns
Brown Patch, also called Rhizoctonia blight, is a
common infectious disease of turfgrass. All turfgrasses grown in Kentucky lawns can be affected by Brown Patch. However, this disease is usually destructive only in tall fescue and perennial ryegrass during warm,
humid weather. While Brown Patch can temporarily harm a lawn's appearance, it usually does not cause permanent loss of turf except in plantings less than
one-year old.
Brown Patch disease is sometimes responsible for poor turf quality, but it is not the only cause of brown spots or bare patches in lawns. You may need to
consider other possible causes of thinning or dead grass. These include:
• improper fertilization
• chemical injury
• mower problems
• dog or insect injury
• localized dry spots
• poor soil drainage
• excessive thatch
• competition from other plants
• buried objects
Symptoms
Areas affected by Brown Patch are initially
roughly circular, varying in size from one to five feet or more. During
early morning hours, fine strands of
grayish, cobwebby
fungal growth (mycelium) may be evident at the margin of actively developing patches. This "smoke ring"
disappears quickly as the dew dries. As an outbreak
progresses and diseased patches coalesce, affected areas may lose the circular appearance and become irregular or diffuse.
On blades of tall fescue, lesions resulting from very
recent infections are olive-green; as they dry, lesions become tan and are surrounded by a thin, brown
border. Brown patch in perennial ryegrass causes blades to wither and collapse. Lesions initially are dark green or grayish green but quickly become tan as
decayed leaves dry. In Kentucky bluegrass, infected leaves exhibit elongated, irregular, tan lesions which are surrounded by a yellow or brown border.
Disease Cycle
Brown Patch is caused by infection of grass foliage and crowns by Rhizoctonia fungi. Rhizoctonia solani is a
very common soilborne fungus and is the cause of Brown Patch symptoms in most instances. Rhizoctonia zeae can also cause Brown Patch in tall fescue under very hot, humid conditions.
Rhizoctonia fungi survive the winter as tiny, brown,
resting bodies (sclerotia) in the soil and thatch layer of the lawn. When environmental conditions are favorable for growth, the sclerotia germinate and produce
cobwebby fungal mycelium, which is the active phase of the fungi. Rhizoctonia fungi often harmlessly
colonize organic matter in the thatch. However, when stressful conditions weaken the grass, Rhizoctonia can infect the plants and cause disease.
Leaf infections are the most common phase of Brown Patch, but infections of crowns and roots sometimes
occur, particularly in seedlings. Rhizoctonia colonizes infected tissues and then forms new sclerotia, thus
completing its life cycle.
Factors Affecting Disease Development
Host
Tall fescue and perennial ryegrass are the lawn
grasses most susceptible to Brown Patch under
Kentucky conditions. Fine fescues (hard fescue,
creeping red fescue, chewings fescue, and sheep
fescue) and zoysia are all moderately susceptible to the disease. Occasionally, Kentucky bluegrass lawns can be affected by Brown Patch, although this grass is less susceptible than others. Seedlings of all grasses are more susceptible to infection than established
plantings.
Weather
Brown Patch is most destructive when the weather is humid and temperatures are stressful to the grass. Thus, in cool-season grasses such as tall fescue and perennial ryegrass, the disease is most severe under high temperatures (highs above 85 F, lows above 60 F). Conversely, in warm-season grasses such as
zoysia, Brown Patch is most severe in humid weather with moderate temperatures (45 - 70 F).
Cultural Conditions
Application of high levels of nitrogen fertilizer,
particularly during spring and summer, favors
development of Brown Patch by producing lush,
succulent growth that is very susceptible to Rhizoctonia
infection. Other factors increase disease severity by creating a humid environment favorable for growth of Rhizoctonia fungi. These factors include: overwatering, watering in late afternoon, poor soil drainage, lack of air movement, shade, a high mowing height, and
overcrowding of seedlings. Excessive thatch, mowing when wet, and leaf fraying by dull mower.
Management
Fertilization
Apply the bulk of nitrogen fertilizer to cool-season turfgrasses in fall and early winter rather than spring or summer. Fall fertilization increases overall root growth of cool-season grasses and reduces their
susceptibility to several diseases. A single fall
application may be applied in November; if making two applications, October and December are good times to fertilize. Avoid overfertilizing, particularly with fertilizers high in nitrogen. Maintain adequate levels of phosphorous and potassium in the soil. Do not
attempt to cure summertime outbreaks of Brown Patch with nitrogen fertilization, as this will simply
aggravate the disease.
Mowing
Set a mower height of no greater than 2 1/2 inches.
A mower height greater than this aggravates Brown Patch by reducing air circulation and allowing more leaf-to-leaf contact, conditions which permit greater fungal growth during humid weather. Mow regularly to promote air circulation and rapid drying of the turf, making the lawn environment less favorable for
fungal growth. To avoid stressing the grass, mow
often enough so that no more than one-third to
one-half of the leaf length is removed at any one mowing. In tall fescue lawns, reducing the mower height to 2 inches or less can further reduce
outbreaks of Brown Patch. However, keep in mind that lawns mowed this closely must be mowed
frequently. In an actively growing tall fescue lawn mowed at 2 inches, it may be necessary to mow
several times a week to prevent removal of more than one-half of the leaf length at one mowing. Never scalp the lawn from 4 inches down to 2 inches or less. During an active outbreak of Brown Patch in hot, humid weather, clipping removal can help
eliminate a food base for the fungus. However, in the absence of an active disease outbreak, returning
clippings to the lawn is a beneficial practice that
returns nutrients to the soil.
Keep the mower blade sharp. A dull blade shreds the leaves, creating an ideal site for infection.
Irrigation
When irrigation is necessary, wet the soil to a depth of at least four inches to promote deep rooting. Check the watering depth by pushing a metal rod or screwdriver into the soil. It will sink easily until it reaches dry soil. Avoid frequent, light waterings. These encourage the grass to develop a shallow root system and frequently provide the surface moisture that Rhizoctonia fungi need to infect the leaves.
If a disease outbreak is evident, water early in the day so that the leaves dry quickly. If the lawn is
watered late in the day, the leaves may remain wet until morning, thus providing long periods of leaf
wetness favorable for infectious fungi. Removing dew, by dragging a hose across the lawn or by very light irrigation during early morning hours, will reduce prolonged leaf wetness and remove leaf exudates that encourage disease development.
Other Cultural Practices
Avoid using excessive seeding rates when seeding or renovating a lawn, as overcrowding can aggravate an outbreak of Brown Patch. See the UK Extension
Publication AGR-52, "Selecting the Right Grass for Your Kentucky Lawn," for information on seeding rates. Selectively prune nearby trees and shrubs to
increase air movement and light penetration, thereby allowing leaf surfaces to dry more quickly. Avoid
applying herbicides during an active outbreak, as these may aggravate the disease.
Fungicides
In an established lawn, fungicide sprays are not
recommended to control Brown Patch. Cultural
practices will usually do a great deal to reduce the disease. Even if an outbreak of Brown Patch occurs, crowns and roots of established plants often survive, and blighted turf begins to recover when cooler weather arrives. So an established, well-managed lawn often will recover from Brown Patch without
fungicide applications.
Heartleaf Philodendron
The heartleaf philodendron is one of the most common and most loved house plants. It can survive in low light. It thrives in medium light. This can be achieved by placing it in an East or West window. If you forget to water the heartleaf
philodendron it is forgiving. However, it prefers to be kept evenly moist. The soil does not need to be wet “mud”.
The heartleaf philodendron is a trailing plant and can get quite long. To make it bushy, trim some of the stems back to the soil line. This will
trigger new thicker growth. Propagate the plant by taking stem tip cuttings and pot them in moist potting medium/soil. The newer cultivars have kept the heartleaf philodendron popularity high:
Lemon Lime - bright green leaves
Brasil - Dark green leaves with bright green stripes
Philodendron Brandtianum - Grey leaves with dark green veins
National Farmers Market Week event
Still Time to Plant
It is harvesting time for lots of vegetables right now, which is leaving empty spaces in our gardens. You can still fill those empty spaces up with mid-season and fall crops. Most stores push seed sales in the springtime, but there is still time to get seeds in the ground.
Start by knowing your planting zones. There are zones 1-13, which 1 being the coldest, and 13 being the warmest. Now there are 1a, 1b, 2a, 2b, etc. So there are 26 zones instead of 13, these can vary 10 degrees or so in difference in the wintertime. You can find out your zone by USDA government maps that you can find online, and usually go by your postal codes. You will also need to know when your first frost date is supposed to occur. There are websites like
Morning Chores, or Old Gardner’s, or Farmer’s Almanac, that have frost calculators on their sites, or you can contact you local extension office for that information as well.
Crops planted now can turn out to be better than planting them in the spring. But you will need to check out maturity dates on the plants you are wanting to set out. Look for maturity dates that range around 60 days, that will leave you some harvesting time before the first frost. Some cool season crops do better now than in the spring, and will be sweeter, as the cooler weather comes in. Cooler weather will be here, before you know it. Beets, and Turnips, have average 60-day maturity, Carrots like cooler weather also. Kale, Collards, and some summer crisp lettuces, will produce well. Peas can also be planted now for fall crops. Some frost hardly plants are cabbage, cauliflower, broccoli, brussels sprouts, mustards make great fall crops.
We can still get several crops in before the first frost. Zucchini, crookneck squash, bush variety beans, is about 55 to 65 maturity dates until first harvest. This still leaves several days for harvest. So there are still Happy Harvesting and Planting days ahead!! ENJOY
Japanese Beetles in the Urban Landscape
by D.A. Potter, M.F. Potter, and L.H. Townsend, Extension Entomologists University of Kentucky College of Agriculture
The Japanese beetle is probably the most devastating pest of urban landscape plants in the eastern United States. Japanese beetles were first found in this country in 1916, after being accidentally introduced into New Jersey. Until that time, this insect was known to occur only in Japan where it is not a major pest.
The eastern US provided a favorable climate, large areas of turf and pasture grass for developing grubs, hundreds of species of plants on which adults could feed, and no effective natural enemies. The beetle thrived under these conditions and has steadily
expanded its geographic range north to Ontario and Minnesota, west to Iowa, Missouri and Arkansas, and south to Georgia and Alabama.
The first Japanese beetles discovered in Kentucky were found on the southern outskirts of Louisville in 1937. Isolated infestations were treated with
insecticides to delay spread of the beetle. During the 1950s and 1960s, beetle populations increased
dramatically and spread in Kentucky and surrounding states. Today, the Japanese beetle infests all of the counties in Kentucky.
Description and Habits
Adult Japanese beetles are 7/16-inch long metallic green beetles with copper-brown wing covers. A row of white tufts (spots) of hair project from under the wing covers on each side of the body. Adults emerge from the ground and begin feeding on plants in June. Activity is most intense over a 4 to 6 week period
beginning in late June, after which the beetles
gradually die off. Individual beetles live about 30 to 45 days.
Japanese beetles feed on about 300 species of plants, devouring leaves, flowers, and overripe or wounded fruit. They usually feed in groups, starting at the top of a plant and working downward. The beetles are most active on warm, sunny days, and prefer plants that are in direct sunlight. A single beetle does not eat much; it is group feeding by many beetles that results in severe damage.
Adults feed on the upper surface of foliage, chewing out tissue between the veins. This gives the leaf a lacelike or skeletonized appearance. Trees that have been severely injured appear to have been scorched by fire. Japanese beetles may completely consume rose petals and leaves with delicate veins. Odors emitted from beetle-damaged leaves seem to be an important factor in the aggregation of beetles on
particular food plants
Adult Japanese beetles are highly mobile and can
infest new areas from several miles away. Usually,
however, they make only short flights as they move
about to feed or lay eggs.
Life Cycle
Egg laying begins soon after the adults emerge from
the ground and mate. Females leave plants in the
afternoon, burrow 2 to 3 inches into the soil in a
suitable area, and lay their eggs--a total of 40 to 60
during their life. The developing beetles spend the
next 10 months in the soil as white grubs. The grubs
grow quickly and by late August are almost full-sized
(about 1 inch long). Grubs feed on the roots of
turfgrasses and vegetable seedlings, doing best in
good quality turf in home lawns, golf courses, parks,
and cemeteries. However, they can survive in
almost any soil in which plants can live.
Mid-summer rainfall and adequate soil moisture are
needed to keep eggs and newly-hatched grubs from
drying out. Females are attracted to moist, grassy
areas to lay their eggs; thus, irrigated lawns and golf
courses often have high grub populations, especially
during otherwise dry summers. Older grubs are
relatively drought resistant and will move deeper into
the soil if conditions become very dry. Japanese
beetle grubs can withstand high soil moisture, so
excessive rainfall or heavy watering of lawns does not
bother them.
As Japanese beetle grubs chew off grass roots, they
reduce the ability of grass to take up enough water to
withstand the stresses of hot, dry weather. As a
result, large dead patches develop in the
grub-infested areas. The damaged sod is not
well-anchored and can be rolled back like a carpet to
expose the grubs. If the damage is allowed to
develop to this stage, it may be too late to save the
turf. Early recognition of the problem can prevent this
destruction.
Japanese beetles overwinter in the grub stage. When
the soil cools to about 60°F in the fall, the grubs begin
to move deeper. Most pass the winter 2 to 6 inches
below the surface, although some may go as deep as
8 to 10 inches. They become inactive when soil
temperature falls to about 50°F. When soil
temperature climbs above 50°F in the spring, the
grubs begin to move up into the root zone. Following
a feeding period of 4-6 weeks, the grubs pupate in an
earthen cell and remain there until emerging as
adults.
From a management standpoint, it is important to
recognize that both the adults and grubs can cause
damage. Moreover, since Japanese beetle adults are
capable of flying in from other areas, controlling one
life stage will not preclude potential problems with the
other. Options for protecting trees, shrubs, and
flowers from adult Japanese beetles are presented
below. Control of the grub stage requires properly
timed applications of a soil insecticide to infested turf.
Diagnosis and control of white grubs in turf is
discussed in a companion publication, Kentucky
Cooperative Extension Service
publications ENT-10, "Controlling White
Grubs" and Entfact 441, "Insecticides for Controlling
of White Grub in Kentucky Turfgrass."
Plant Selection
Careful selection of plant species when replacing or
adding to your landscape is the key to avoiding
annual battles with Japanese beetles. Some species
and cultivars are highly preferred by the adults and
should be avoided where the beetle is abundant.
Plants that are especially prone to damage include
roses, grapes, lindens, sassafras, Norway maple,
Japanese maple, purple-leaf plum, and others. Many
varieties of flowering crabapples are also severely
attacked by the beetles, although some cultivars are
resistant.
Japanese beetles are also fond of certain weeds and
non-cultivated plants such as bracken, elder,
multiflora rose, Indian mallow, poison ivy, smartweed,
and wild grape. Elimination of these plants whenever
practical destroys these continuous sources of
infestation.
Although plant selection is important, other
approaches
must obviously
be used to
protect
susceptible
plants that are
already
established in
landscapes.
Physical Removal and Exclusion
Removing beetles by hand may provide adequate protection for small plantings, especially when beetle numbers are low. The presence of beetles on a plant attracts more beetles. Thus, by not allowing beetles to accumulate, plants will be less attractive to other
beetles.
One of the easiest ways to remove Japanese beetles from small plants is to shake them off early in the morning when the insects are sluggish. The beetles may be killed by shaking them into a bucket of soapy water. Highly valued plants such as roses can be
protected by covering them with cheesecloth or other fine netting during the peak of beetle activity.
Chemical Control
Many insecticides are labeled for use against adult Japanese beetles. Examples include pyrethroid
products such as cyfluthrin (Tempo, Bayer Advanced Lawn & Garden Multi-Insect Killer), bifenthrin (TalstarOne, Onyx), deltamethrin (Deltagard), lambda cyhalothrin (Scimitar, Spectracide Triazicide),
esfenvalerate (Ortho Bug-B-Gon Garden &
Landscape Insect Killer) and permethrin (Spectracide Bug Stop Multi-Purpose Insect Control Concentrate and other brands). Carbaryl (Sevin and other brand names) too is effective. The pyrethroid products
generally provide 2-3 weeks protection of plant foliage while carbaryl affords 1-2 weeks protection. For those seeking a botanical alternative, Neem products such as Azatrol or Neem-Away (Gardens Alive), or Pyola (pyrethrins in canola oil) provide about 3-4 days
deterrence of Japanese beetle feeding. Insecticidal soap, extracts of garlic, hot pepper, or orange peels, and companion planting, however, are generally
ineffective.
With all products, foliage and flowers should be
thoroughly treated. The application may need to be repeated to prevent reinfestation during the adult flight period. Follow label directions and avoid spraying
under windy conditions or when bees are foraging.
Be sure the insecticide is registered for use on the plant or crop you intend to spray. If it is a food crop, note the minimum number of days that must be ob-served between the date of the last application and the date of harvest.
Because Japanese beetles are attracted to favored host plants from a considerable distance, controlling white grubs in the lawn will not protect landscape plants from adult feeding.
Japanese Beetle Traps
Japanese beetle traps are sold in many garden
centers. Commercially available traps attract the
beetles with two types of baits. One mimics the scent of virgin female beetles and is highly attractive to males. The other bait is a sweet-smelling food-type lure that attracts both sexes. This combination of
ingredients is such a powerful attractant that traps can draw in thousands of beetles in a day.
Unfortunately, research conducted at the University of Kentucky showed that the traps attract many more beetles than are actually caught. Consequently,
susceptible plants along the flight path of the beetles and in the vicinity of traps are likely to suffer much more damage than if no traps are used at all.
In most landscape situations, use of Japanese beetle traps probably will do more harm than good. If you experiment with traps, be sure to place them well away from gardens and landscape plants.
Mention or display of a trademark, proprietary
product, or firm in text or figures does not constitute an endorsement and does not imply approval to the exclusion of other suitable products or firms.
CAUTION! Pesticide recommendations in this
publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.
Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY
PESTICIDE!
Source: https://entomology.ca.uky.edu/ef451
Bonsai Class
By: Kara Back, Taylor County Horticulture Agent
The Art of Bonsai
What is bonsai?
Bonsai is the words potted plant in Japanese. Traditional plants commonly used for bonsai are outdoor plants like maple trees and evergreens. A modern way of creating bonsai is to use tropical or house plants. Using these types of plants allows ancient-looking growth to appear much faster, requiring no dormant/winter care. Bonsai does require quite a bit of time over many years. The small root system of bonsai will
require frequent watering. In some instances
every day.
The Ficus varieties are often used for bonsai. You can buy a bonsai pre-trained or create your own. Normally the older the bonsai the higher the price. Creating your own bonsai can actually be
therapeutic. To shape the trees you will need a soft copper wire or a covered aluminum wire. Use smaller gauge wire to wrap around smaller
branches. This wire will allow you to shape the tree just the way you want it. Take the wire off as soon as the branch holds the shape, and before the tree starts to grow around it. Trimming is important to keep the bonsai in shape and size.
Gardening by Month—August
Ornamentals
Vegetables
Fruit
• Compost or till under residues from harvested crops.
• Sow seeds of beans, beets, spinach, and turnips now for the fall garden. Spinach may germinate better if seeds are refrigerated for one week before planting.
• Cure onions in a warm, dry place for two weeks before storing.
• Broccoli, cabbage, and cauliflower transplants should be set out now for the fall garden.
• Begin planting lettuce and radishes for fall now.
• Pinch the growing tips of gourds once adequate fruit is achieved. This directs energy into ripening fruits, rather than vine production.
Source: Missouri Botanical Garden
• Prop up branches of fruit trees that are threatening to break under the weight of a heavy crop.
• Protect ripening fruits from birds by covering plants with a netting.
• Continue to spray ripening fruits to prevent brown rot fungus.
• Thornless blackberries are ripening now.
• Watch for fall webworm activity now.
• Cultivate strawberries. Weed preventers can be applied immediately after fertilizing.
• Spray peach and other stone fruits now to protect against peach tree borers.
• Fall-bearing red raspberries are ripening now.
• Sprays will be necessary to protect late peaches from oriental fruit moth damage.
Lawns
• Continue spraying roses that are susceptible to black spot and other fungus diseases.
• Annuals may appear leggy and worn now. These can be cut back hard and fertilized to produce a new flush bloom.
• Deadhead annuals and perennial as needed.
• Divide oriental poppies now.
• Feed mums, asters and other fall-blooming perennials for the last time.
• Roses should receive no further nitrogen fertilizer after August 15th.
• Powdery mildew on lilacs is unsightly, but causes no harm and rarely warrants control, though common rose fungicides will prove effective.
• Madonna lilies, bleeding heart (Dicentra) and blood-root (Sanguinaria) can be divided and replanted.
• Divide bearded iris now. Discard old center sections and borer damaged parts. Replant so tops of rhizomes are just above ground level.
• Prune to shape hedges for the last time this season.
• Order bulbs now for fall planting.
• Zoysia lawns can receive their final fertilizer application now.
• Apply insecticides now for grub control on lawns being damaged by their activity.
• Lawns scheduled for renovation this fall should be killed with Roundup now. Have soil tested to determine fertility needs.
• Dormant lawns should be soaked now to encourage strong fall growth.
• Verify control of lawn white grubs from earlier insecticide applications.
Mozzarella Basil Chicken with Roasted Grape Tomatoes
