Frost

With the cooler temperatures this week and possible frost forecasted, it seemed like a good time to talk about frost.

Frost forms when an outside surface cools past the dew point.  The dew point is the point where the air gets so cold, the water vapor in the atmosphere turns into liquid. This liquid freezes.  If it gets cold enough, little bits of ice, or frost, form. The ice is arranged in the form of ice crystals.

Types of Frost
Radiation frost is frost in the form of tiny ice crystals that usually shows up on the ground or exposed objects outside. 

Advection frost is a collection of small ice spikes. Advection frost forms when a cold wind blows over the branches of trees, poles, and other surfaces.

Window frost forms when a glass window is exposed to cold air outside and moist air inside. Window frost is familiar to winter residents of cold climates. Indoor heat and cold outdoor temperatures cause this type of frost.

Rime is frost that forms quickly, usually in very cold, wet climates. Rime also forms in windy weather. Rime sometimes looks like solid ice.

Frost and Plants
Frost damage occurs when ice forms inside the plant tissue and injures the plant cells.  Frost damage may have a drastic effect upon the entire plant or affect only a small part of the plant tissue, which reduces yield, or merely product quality.

Direct frost damage occurs when ice crystals form inside the protoplasm of cells, whereas indirect damage can occur when ice forms inside the plants but outside of the cells.  It is believed that direct frost damage causes problems for protoplasmic structures.

Although the evidence is not strong, it seems that the rate of thawing after a freeze is also partially related to the amount of damage. Citrus growers in southern California commonly believe that slowing the warming process after a freeze night can reduce frost damage. In fact, growers justify operating wind machines longer into the morning following a freeze night in order to slow the thawing process.

Usually there are still a couple of good weeks of weather after the first frost.  While the first frost announces the coming of winter there are some things one can do to protect  plants:

• Harvest early
• Irrigate before the frost
• Cover your plants
• Irrigate during the frost
• Chemical sprays
• Heaters and wind machines

Protect your plants for the remainder of the growing season.  Soon winter will be here and we will be begin our winter garden tasks.

Additional Information

Understanding Frost - Cornell University

Frost protection: Physiology and Critical Temperatures - United Nations

Frost - National Geographic

IPM Notes from October 17th 2013

Notes: IPM for October 10th was rained out.  This will be the last official field day and crop report. It is likely that next Thursday will be harvest day for the popcorn, and harvest for the peanuts is still several weeks away.  Winter annuals are germinating and sprouting in the fields.  Deer are actively grazing the soybeans and peanuts.

Pheromone Traps

Trap #1 - Black Cutworm
1 possible lygus bug

Trap #2 - Corn Earworm
1 fly, 1 mystery moth (still unidentified), 1 noctuid, 1 Fall Armyworm moth, 1 beetle, 1 lygus bug.

Trap #4 - Fall Armyworm
10 Fall Armyworm  moths, 1 mayfly

Traps were retrieved for storage.

Field Corn Field
It has not yet been harvested. The word is that it was such a small field that they didn’t get a round tuit. (a round to it) The stalks are very dry and the ears are folding down. This is prime trouble if there were turkeys around. When the ears drop it is exactly at the right level to be picked clean. Yield should be around 170 bushels (our estimate was 177.25).

Popcorn Field
The tops of the ears have been heavily eaten by the birds. Where the tops have been eaten mold is forming. Moisture content is still too high to harvest without the need for further drying. Perhaps by next week we will be able to harvest.

Cover Crop Field

• Buckwheat is reseeding.  
• Soybeans are showing pod and stem blight.
• Sweet Corn Field
• The rye is up.

Hay Field
Winter wheat has been planted and is now coming up.

Soybean Field
Fully defoliated. Pod and stem blight is showing up, but will not affect crop yield due to maturity of crop and lateness of season. Moisture content still too high for harvest.

Wheat/Soybean Field
Foliage is turning and beginning to drop off. Stinkbug population is a concern due to their numbers, piercing of the pods, and the effect of keeping the soybeans green – delaying maturation of the plants.

Demonstration Plots

Tomatoes have been harvested and the plot cleared.

Peppers have been harvested and the plot cleared.

Groundhog radishes (Daikon) have germinated in the compost, quinoa, and cover plots.

Peanuts still exhibit potassium deficiency. Peanuts have grown in size, but the covering inside the shell is pink showing that they are not yet mature. We have noted that something is boring into the peanuts underground. We have not found the culprit.



A very special thank you to Roger Arnold for compiling this season's field notes and reports.

Weed of the Week - Oxeye Daisy

The oxeye daisy (Chrysanthemum leucanthemum) is short-lived perennial.  Originally brought here from Europe intentionally as an ornamental and incidentally as a contaminant of imported hay and grain seeds.

Natural History

Oxeye daisy plant with ray flower (A), disc flower

(B), seed (C), lower leaf detail (D), and rootstalk (E) - MSU

Leaves - Montana Weed Control Association

Flower - Oklahoma Biological Survey

The ox-eye daisy is a member of the Asteraceae family.  It is a perennial herbaceous plant with thin 1- 2' tall stems typically branch above to produce two or more flower heads; smells like sage. It is the only large white daisy that has escaped gardens.  The leaves are alternate, lobed and deeply cut.  The root system is densely fibrous and forms offsets from short rhizomes.

The ox-eye daisy looks like some asters and is often confused with the ornamental Shasta daisy. The Shasta daisy's flowerheads tend to be larger than the ox-eye and it is usually taller than the ox-eye daisy.

Management Strategies
Preventing spread and minimizing establishment is critical in the control of any weed.  For small patches hoe or hand-pull seedlings and young plants. This is most effective when done before oxeye daisy flowers and the seed is dispersed.  A wildflower seed mix may contain ox eye daisy, so read the label carefully before using any wildflower seed mix. Biological controls have not yet been developed to manage oxeye daisies.  Some other methods for control are:

• Hand pulling and grubbing (i.e. digging up the roots)
• Tilling
• Mowing
• Grazing
• Chemicals

See  Oxeye Daisy for details on management strategies.


Additional Information

Oxeye Daisy - Virginia Tech

Invasive Plants Ox-eye Daisy - Montana State University

Oxeye Daisy Identification and Control - Salt Lake County

IPM Notes from October 3, 2013

Pheromone Trap Results

Trap #1 Black Cutworm
No insects trapped, 1 spider

Trap #2 Corn Earworm
No insects trapped

Trap #4 Fall Armyworm
4 Fall Armyworm, 1 True Armyworm, no other insects

Field Corn Field
This field has not been harvested. We do not know why. However, we are observing that the stalks are becoming more brittle with many of the tops broken down because of the birds. We also noted that the ears have now broken downward so that the ears are pointing toward the ground. We believe that this field is very susceptible to storm damage and are unsure if it can be harvested.

Popcorn Field
The popcorn is being decimated by the birds. Many ears are eaten down halfway or more. It may be a race to see if the birds eat it all or if we get to harvest some.

Note: Our unidentified moths are now in the pollinator strip, the strip between the cover field and popcorn, and in the herb demonstration plot.

Hay Field
This field has been chemically ‘burned’ and the foliage there is dying. This is in preparation for rotating this field into wheat.

Sweet Corn Field
The field was drilled and the grain – we presume rye – is now coming up.

Wheat/Soybean Field
There are Harlequin bugs present. There are also a large number of stink bugs – predominately Brown Marmorated. However, we did discover another species and will take it to the office for positive identification – it may be a predator. (Lise emailed back that it is probably the nymph stage of the green stinkbug.) We are also finding several wooly caterpillars. Deer are still grazing the margins of the field heavily.

Pollinator Strip
There are still flowers blooming down low even though the weeds are upwards of 5 – 6 feet tall.

Demonstration Plots
 
Tomato
Ramapo production continues to outstrip SuperSonic production in the Fall.

Peanuts
Peanuts are showing greater potassium deficiency – possibly allowing some disease vectors to begin.

Compost plot
Has been cleared and planted with groundhog radish.

Quinoa plot
Has also been planted with groundhog radish.

Note: We found another interesting caterpillar this week. This one was on the Basil in the herb garden and was the same dark red color as the stalk of the plant.

Weeds identified this week:

• Henbit
• Wild Geranium
• Spiny Amaranth
• Amaranth
• Goose Grass
• Fall Panicum
• Shepherd’s Purse
• Pineapple Weed
• Lamb’s Quarter
• FoxTail
• VelvetLeaf
• MaresTail
• Pennsylvania Smartweed
• JimsonWeed
• Curly Dock
• Chicory
• Yellow NutSedge
• Bedstraw
• Dandelion
• Plantain – broad and narrow leaf
• OxEye Daisy

Thanks to Roger for compiling the notes for the week.

Pest of the Week - Lygus Bugs

Lygus bugs are small, oval-shaped insects that feed on a variety of crops and weeds. Several species infest canola and alfalfa. 

Natural History

Tarnished Plant Bug (Lygus lineolaris) - State of Maine

Washington State University

Young nymphs are tiny and light green in color. Older nymphs are larger, with noticeable black dots on their back, and well-developed wing pads. Young tarnished plant bug nymphs can easily be confused with aphids.

In alfalfa, a new generation can mature about the time the alfalfa is cut for forage. The new lygus bug generation leaves alfalfa seeking another crop.

The tarnished plant bug is among the most damaging of the true bugs and is known to transmit plant diseases. The bugs use their needle-like mouthparts to extract plant juices. Their feeding causes terminal growth to be yellowed or distorted thereby reducing plant growth and causing them to appear unthrifty. Leaves from damaged buds are sometimes ragged and discolored.  Adults and nymphs of Lygus lineolaris feed by sucking plant juices and a watery saliva is simultaneously injected into the feeding site to aid in the breakdown of plant tissues.


Management Strategies

Lygus bugs have several natural control agents. A tiny fairy wasp (Anaphes ovijentatus) in the family Mymaridae parasitises the eggs of the lygus bug.  Nabid plant bugs, big-eyed bugs, and spiders occasionally prey on young lygus bug nymphs. A European wash, Peristenus digoneutis, has been introduced into alfalfa fields in eastern North America where it parasitises about 40 percent of the tarnished plant bugs. One of the few parasitoids of lygus adults is a tachinid fly, Alophorella spp.

Additional Information

Plant Bugs (Miridae) - American Museum of Natural History

Insect Lygus Bugs - Washington State University 

Lygus Bugs - North Dakota State University 

Tarnished Plant Bug - Dept. of Agriculture, State of Maine 

Lygus Bugs - Manitoba Agriculture 

Family Mymaridae - UC Riverside 

Family Mymaridae - USDA