22 March 2016 |

Horticulture Newsletter 2016, No. 12

Written by K-State Horticulture Newsletter - Newsletters

Video of the Week:
Caring for Knockout Roses

Upcoming Events:

Hands-On Mushroom Cultivation Workshop
 
Friday, April 1 or Saturday, April 2
 
Topics Covered:
Growing oyster mushrooms on straw and sawdust
Inoculating shiitake mushroom logs (hands-on)
Growing winecap mushrooms in woodchips or straw mulch
Log selection and harvest
 
Each participant will receive:
Oyster Mushroom Production Bag
Inoculated Shiitake Log
 
Cost of the workshop: $25
 
For details, see  http://www.reno.k-state.edu/docs/Mushroom%20workshop%20flyer.pdf  or call
620-662-2371.

Vegetables:
Frost Proof Vegetable Plants 

cool season vegetables
Certain vegetables can withstand cold spring temperatures as long as they have been toughened up by gradually exposing them to sunlight and outdoor temperatures. This “hardening off” process usually takes about a week.
 
Reducing watering and temperature is the key to toughening up transplants. If possible, move transplants outside for a portion of each day. Start by placing them in a shady, protected location and gradually move them into a more exposed, sunny location as the week progresses. Hardened off cabbage, broccoli, cauliflower and onions can withstand temperatures near 20 F without being killed.  Lettuce plants are not quite as tough but will be okay if exposed to temperatures in the mid 20s.
Don’t hesitate to put these plants out now if extreme cold is not forecast. (Ward Upham)

Asparagus Time

Asparagus
Asparagus is one of those vegetables where freshness is incredibly important. If you have never eaten asparagus fresh out of the garden, try it. It may convince you to grow some of your own. For those who have an asparagus patch, the new spears should be appearing soon. The first asparagus that comes through the ground always seems to take a long time to reach harvest size. That is because asparagus growth is temperature dependent. The higher the day and nighttime temperatures, the faster it grows. Also, the longer the spear, the quicker the growth. As the season progresses and spears get longer, the growth rate increases.
 
Harvest asparagus by snapping or cutting. Snapping is quick and easy. Simply bend the stalk near the base until it breaks. Snapped ends dry quickly so refrigerate or use soon after harvest. If you cut asparagus, use a sharp knife to detach the spears slightly below ground level. This base is woodier than snapped asparagus, so it doesn't lose water as quickly. Cut off woody ends before cooking. (Ward Upham)

Herbicides for Home Gardens

vegetable garden
Though mulches and hoeing are usually all that is needed for small vegetable gardens, homeowners with large areas may need the help of herbicides to keep ahead of the weeds. One preemergence and one postemergence herbicide can be used on home vegetable gardens.
 
The preemergence herbicide is trifluralin. Preemergence herbicides kill weed seeds as they germinate. They usually have no effect on weeds that have emerged. Therefore, they must be put on either before weeds come up in the spring or after weeds have been physically removed. The preemergence herbicide trifluralin is sold under the trade names of Treflan, Preen, Miracle-Gro Garden Weed Preventer, Gordon's Garden Weed Preventer Granules and Monterey Vegetable and Ornamental Weeder.
 
The postemergence herbicide is sethoxydim. This product only kills grasses; broadleaves are not affected. It can be sprayed directly over the top of many vegetables. Sethoxydim is sold as Poast, Monterey Grass Getter, and Hi-Yield Grass Killer. A second postemergence herbicide called fluazifop-p-butyl is labeled for commercial growers as Fusilade, but I haven't found vegetables listed on the homeowner labels, “Over the Top Grass Killer” and “Grass-No-More.” Also, the other homeowner products mentioned above often do not have as many vegetables on the label as the commercial products. Even among the homeowner products with the same active ingredient, there may be slight differences among labels. Check product labels to be sure the crop is listed. Here is a list of herbicides and the crops for which they are labeled. Many of these crops have application restrictions. For example, trifluralin can be used on asparagus, but must be applied before spears emerge. (Ward Upham)

Fruit:
Apple Tree Sprays

Cedar-Apple rust
Two common diseases on apple trees are cedar apple rust and apple scab. Though some apple varieties are resistant to these diseases — including Liberty, Jonafree, Redfree, Freedom, Williams Pride and Enterprise — most varieties are susceptible. For a listing of the disease resistance of various cultivars, go to: http://extension.missouri.edu/explorepdf/agguides/ hort/g06022.pdf
Fungicide sprays during April and May are critical to preventing disease on susceptible varieties. With the warm spring this year, we may have to start sprays in March. The first spray should go down when leaves appear. A fungicide that is available to homeowners and very effective for control of apple scab and cedar apple rust is myclobutanil (Immunox). There are several formulations of Immunox but only one is labeled for fruit. Check the label.
 
Sprays should be done on a 7- to 10-day schedule to keep the protective chemical cover on the rapidly developing leaves and fruit. An insecticide will need to be added to this mixture after petal drop to prevent damage from codling moths that cause wormy apples. Methoxychlor or malathion can be used as an insecticide. In order to protect bees, DO NOT use any insecticide during bloom.  Check the malathion label before purchase as not all labels list fruit.
 
Although gardeners may continue to use myclobutanil throughout the season, certain other fungicides are more effective on summer diseases such as sooty blotch and fly speck. Consider switching to Captan or to a fruit spray mixture about June 1. A spreader-sticker can be added to the fungicide-insecticide chemical mixture to improve the distribution and retention of the pest control chemicals over the leaves and fruit. A hard, driving rain of about 1 inch or more will likely wash chemicals from the leaves and fruit. In such cases, another application should be made. You can find information on controlling insects and diseases on fruit trees in our publication titled "Fruit Pest Control for Home Gardens" at http://www.ksre.ksu.edu/bookstore/pubs/c592.pdf  Below is the spray schedule I use. Sprays are applied ever 10 days until 2 weeks before harvest.
 
Leaves Appear: Immunox
Petal Drop: Add malathion to the Immunox and so the mixture is Immunox + malathion
June 1: Replace Immunox with Captan. The mixture is now Captan + malathion
Stop spraying 2 weeks before harvest. (Ward Upham)

Turfgrass:
Core Aeration of Cool-Season Grass

core aerator
If you are planning to core-aerate your tall fescue or Kentucky bluegrass lawn this spring, March or early-April is the time. Coring early in the spring gives cool-season lawns a chance to recover before crabgrass and other warm-season annual weeds start to germinate.
 
Core-aerating is one of the best things you can do for your lawn. It relieves compaction, hastens thatch decomposition, increases water infiltration and helps promote better root growth. Pay attention to the soil moisture level when coring. The soil should easily crumble when worked between the fingers. If it is too wet, the machine's tines will plug and it will merely punch holes in the wet soil, which increases compaction. If it is too dry, the tines will not be able to penetrate deeply enough to be of benefit. (Ward Upham)

Ornamentals:
Hackberry Psyllid, the Tiny "Gnat" Invading Homes

Hackberry psyllid
It is rare to find a hackberry tree without round growths on the underside of the leaves. These bumps, or galls, are the result of a tiny insect known as the hackberry psyllid. Hackberry is the only known host of this pest.
 
The adults of these insects are tiny and resemble miniature cicadas. They are dark reddish-brown with mottled wings. Most emerge from the galls during warm days in September and are very annoying as they gather around window screens seeking entry into the house. They are tiny enough to crawl through the openings in most screens. In the spring, the adults become active about the time the leaf buds open. The female lays her eggs on the underside of the developing leaves. Egg hatch occurs in 7 to 10 days, and the young nymphs begin to feed immediately. The leaf reacts to the feeding by producing a pouch or gall that entirely encloses the nymph.
 
Control is difficult. Adults that invade homes can be collected by using a vacuum sweeper but the bag should be discarded or the adults will escape. Since these insects do not seriously affect the vitality of the hackberry tree, control is usually not recommended. (Ward Upham)

Video of the Week:
Caring for Knockout Roses

Upcoming Events:

Hands-On Mushroom Cultivation Workshop
 
Friday, April 1 or Saturday, April 2
 
Topics Covered:
Growing oyster mushrooms on straw and sawdust
Inoculating shiitake mushroom logs (hands-on)
Growing winecap mushrooms in woodchips or straw mulch
Log selection and harvest
 
Each participant will receive:
Oyster Mushroom Production Bag
Inoculated Shiitake Log
 
Cost of the workshop: $25
 
For details, see  http://www.reno.k-state.edu/docs/Mushroom%20workshop%20flyer.pdf  or call
620-662-2371.

Vegetables:
Frost Proof Vegetable Plants 

cool season vegetables
Certain vegetables can withstand cold spring temperatures as long as they have been toughened up by gradually exposing them to sunlight and outdoor temperatures. This “hardening off” process usually takes about a week.
 
Reducing watering and temperature is the key to toughening up transplants. If possible, move transplants outside for a portion of each day. Start by placing them in a shady, protected location and gradually move them into a more exposed, sunny location as the week progresses. Hardened off cabbage, broccoli, cauliflower and onions can withstand temperatures near 20 F without being killed.  Lettuce plants are not quite as tough but will be okay if exposed to temperatures in the mid 20s.
Don’t hesitate to put these plants out now if extreme cold is not forecast. (Ward Upham)

Asparagus Time

Asparagus
Asparagus is one of those vegetables where freshness is incredibly important. If you have never eaten asparagus fresh out of the garden, try it. It may convince you to grow some of your own. For those who have an asparagus patch, the new spears should be appearing soon. The first asparagus that comes through the ground always seems to take a long time to reach harvest size. That is because asparagus growth is temperature dependent. The higher the day and nighttime temperatures, the faster it grows. Also, the longer the spear, the quicker the growth. As the season progresses and spears get longer, the growth rate increases.
 
Harvest asparagus by snapping or cutting. Snapping is quick and easy. Simply bend the stalk near the base until it breaks. Snapped ends dry quickly so refrigerate or use soon after harvest. If you cut asparagus, use a sharp knife to detach the spears slightly below ground level. This base is woodier than snapped asparagus, so it doesn't lose water as quickly. Cut off woody ends before cooking. (Ward Upham)

Herbicides for Home Gardens

vegetable garden
Though mulches and hoeing are usually all that is needed for small vegetable gardens, homeowners with large areas may need the help of herbicides to keep ahead of the weeds. One preemergence and one postemergence herbicide can be used on home vegetable gardens.
 
The preemergence herbicide is trifluralin. Preemergence herbicides kill weed seeds as they germinate. They usually have no effect on weeds that have emerged. Therefore, they must be put on either before weeds come up in the spring or after weeds have been physically removed. The preemergence herbicide trifluralin is sold under the trade names of Treflan, Preen, Miracle-Gro Garden Weed Preventer, Gordon's Garden Weed Preventer Granules and Monterey Vegetable and Ornamental Weeder.
 
The postemergence herbicide is sethoxydim. This product only kills grasses; broadleaves are not affected. It can be sprayed directly over the top of many vegetables. Sethoxydim is sold as Poast, Monterey Grass Getter, and Hi-Yield Grass Killer. A second postemergence herbicide called fluazifop-p-butyl is labeled for commercial growers as Fusilade, but I haven't found vegetables listed on the homeowner labels, “Over the Top Grass Killer” and “Grass-No-More.” Also, the other homeowner products mentioned above often do not have as many vegetables on the label as the commercial products. Even among the homeowner products with the same active ingredient, there may be slight differences among labels. Check product labels to be sure the crop is listed. Here is a list of herbicides and the crops for which they are labeled. Many of these crops have application restrictions. For example, trifluralin can be used on asparagus, but must be applied before spears emerge. (Ward Upham)

Fruit:
Apple Tree Sprays

Cedar-Apple rust
Two common diseases on apple trees are cedar apple rust and apple scab. Though some apple varieties are resistant to these diseases — including Liberty, Jonafree, Redfree, Freedom, Williams Pride and Enterprise — most varieties are susceptible. For a listing of the disease resistance of various cultivars, go to: http://extension.missouri.edu/explorepdf/agguides/ hort/g06022.pdf
Fungicide sprays during April and May are critical to preventing disease on susceptible varieties. With the warm spring this year, we may have to start sprays in March. The first spray should go down when leaves appear. A fungicide that is available to homeowners and very effective for control of apple scab and cedar apple rust is myclobutanil (Immunox). There are several formulations of Immunox but only one is labeled for fruit. Check the label.
 
Sprays should be done on a 7- to 10-day schedule to keep the protective chemical cover on the rapidly developing leaves and fruit. An insecticide will need to be added to this mixture after petal drop to prevent damage from codling moths that cause wormy apples. Methoxychlor or malathion can be used as an insecticide. In order to protect bees, DO NOT use any insecticide during bloom.  Check the malathion label before purchase as not all labels list fruit.
 
Although gardeners may continue to use myclobutanil throughout the season, certain other fungicides are more effective on summer diseases such as sooty blotch and fly speck. Consider switching to Captan or to a fruit spray mixture about June 1. A spreader-sticker can be added to the fungicide-insecticide chemical mixture to improve the distribution and retention of the pest control chemicals over the leaves and fruit. A hard, driving rain of about 1 inch or more will likely wash chemicals from the leaves and fruit. In such cases, another application should be made. You can find information on controlling insects and diseases on fruit trees in our publication titled "Fruit Pest Control for Home Gardens" at http://www.ksre.ksu.edu/bookstore/pubs/c592.pdf  Below is the spray schedule I use. Sprays are applied ever 10 days until 2 weeks before harvest.
 
Leaves Appear: Immunox
Petal Drop: Add malathion to the Immunox and so the mixture is Immunox + malathion
June 1: Replace Immunox with Captan. The mixture is now Captan + malathion
Stop spraying 2 weeks before harvest. (Ward Upham)

Turfgrass:
Core Aeration of Cool-Season Grass

core aerator
If you are planning to core-aerate your tall fescue or Kentucky bluegrass lawn this spring, March or early-April is the time. Coring early in the spring gives cool-season lawns a chance to recover before crabgrass and other warm-season annual weeds start to germinate.
 
Core-aerating is one of the best things you can do for your lawn. It relieves compaction, hastens thatch decomposition, increases water infiltration and helps promote better root growth. Pay attention to the soil moisture level when coring. The soil should easily crumble when worked between the fingers. If it is too wet, the machine's tines will plug and it will merely punch holes in the wet soil, which increases compaction. If it is too dry, the tines will not be able to penetrate deeply enough to be of benefit. (Ward Upham)

Ornamentals:
Hackberry Psyllid, the Tiny "Gnat" Invading Homes

Hackberry psyllid
It is rare to find a hackberry tree without round growths on the underside of the leaves. These bumps, or galls, are the result of a tiny insect known as the hackberry psyllid. Hackberry is the only known host of this pest.
 
The adults of these insects are tiny and resemble miniature cicadas. They are dark reddish-brown with mottled wings. Most emerge from the galls during warm days in September and are very annoying as they gather around window screens seeking entry into the house. They are tiny enough to crawl through the openings in most screens. In the spring, the adults become active about the time the leaf buds open. The female lays her eggs on the underside of the developing leaves. Egg hatch occurs in 7 to 10 days, and the young nymphs begin to feed immediately. The leaf reacts to the feeding by producing a pouch or gall that entirely encloses the nymph.
 
Control is difficult. Adults that invade homes can be collected by using a vacuum sweeper but the bag should be discarded or the adults will escape. Since these insects do not seriously affect the vitality of the hackberry tree, control is usually not recommended. (Ward Upham)

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