Corn and Wheat: Growth, Varieties, Pests, and Diseases

What is the botanical name for corn?

Zea mays

To which family does corn belong?

Poaceae (Gramineae)

Where did the origin of corn begin?

Central Mexico, around 8000 - 9000 years ago

From which wild grass was corn domesticated?

Teosinte

What are the four major components of a corn kernel?

Starch, fiber, protein, and oil

What is a common use of corn in grocery stores?

Approximately 4,000 items list corn ingredients on the label.

What type of plant is corn in terms of reproductive organs?

Monoecious, with male and female organs on separate parts.

What is the male flower structure of corn called?

Tassel

What are the female flower structures of corn commonly known as?

Ears

What is dent corn primarily used for?

Livestock feed, silage, and food products like cornbread and tortilla chips.

What distinguishes flint corn from other types?

It has a hard outer layer that protects the soft endosperm inside.

How does popcorn pop?

Water inside the kernel expands when heated until the kernel bursts.

What is sweet corn bred for?

To have plump, juicy kernels with a high level of natural sugar.

What is high-starch corn used for?

Ethanol production.

What is genetically modified corn engineered for?

Resistance to herbicides and to produce proteins that kill specific insect pests.

What is Bt corn?

Corn hybrids with genes from Bacillus thuringiensis that produce insecticidal proteins.

What percentage of corn acreage was planted with Bt corn in 2022?

84%

What are the two main growth stages of corn?

Vegetative stages and reproductive stages.

What does the VE stage in corn growth indicate?

Emergence of the plant.

What damage does the fall armyworm cause to corn?

Circular to irregular holes in foliage and skeletonized leaves.

What is the significance of the tassel in corn plants?

It is the male inflorescence that produces pollen.

What is the purpose of silage made from corn?

To provide fodder for livestock.

What is the main characteristic of specialty corn?

Designed for specific uses like high starch or high oil content.

What does the R1 stage in corn reproductive growth indicate?

Silking stage, when the silk emerges from the ear.

What are organic methods for controlling fall armyworms?

Biological control by natural enemies and application of Bacillus thuringiensis.

What symptoms indicate a mite infestation on plants?

Leaves stippled with yellow, bronzed appearance, webbing on underside of leaves.

How can systemic insecticides be used in mite management?

Systemic insecticides can be used if mites become problematic.

What are the two species of corn rootworms that cause severe damage?

Western corn rootworms and northern corn rootworms.

What is a recommended management practice for corn rootworms?

Rotate fields out of corn production every 4 to 5 years.

What is the preferred feeding site for corn earworms?

The ear of the corn plant.

What are the initial characteristics of corn earworm eggs?

Eggs are creamy white initially but develop a brown-red ring after 24 hours.

What is the impact of heavy aphid infestations on corn plants?

Curled leaves, stunted plants, and honeydew secretions promoting sooty mold.

What is the economic threshold level for aphid control?

Control is generally not warranted until aphids reach damaging levels.

What are the symptoms of northern leaf blight?

Elliptical gray-green lesions on leaves that become pale gray to tan.

What is the causal organism of northern leaf blight?

A fungus.

What management practices can reduce northern leaf blight?

Proper tillage, crop rotation with non-host crops, and growing resistant varieties.

What are the symptoms of Giberrella stalk and ear rot?

Wilting plants, color change from light to dull green, and red mold at ear tips.

What is the causal organism for Giberrella stalk and ear rot?

A fungus.

What management practices help reduce Giberrella stalk and ear rot?

Adequate fertilization, irrigation, and controlling insects.

What are the symptoms of anthracnose in corn plants?

Small water-soaked spots on leaves that enlarge and may coalesce into large patches.

What is the causal organism of anthracnose?

A fungus.

What management practices can help reduce anthracnose incidence?

Planting resistant hybrids, rotating crops, and plowing debris into soil.

What are the symptoms of bacterial stalk rot?

Plants lodging, internodes turning brown and mushy, with a foul odor.

What conditions favor the emergence of bacterial stalk rot?

Overhead irrigation, high rainfall, high temperatures, and humidity.

What management practices can prevent bacterial stalk rot?

Plowing crop debris into soil and planting in well-draining soil.

What are the symptoms of maize dwarf mosaic virus?

Chlorotic spots and streaks on leaves that develop into a mottled pattern.

What management practices are recommended for maize dwarf mosaic virus?

Controlling aphid populations and removing Johnson grass as it can act as a virus reservoir.

Where did wheat originate?

In the Middle East, specifically the Fertile Crescent, present-day Iraq, Syria, and Iran.

When did the cultivation of wheat begin?

After 8000 BC.

What is the botanical name for common wheat?

Triticum aestivum.

What is the ploidy level of hexaploid wheat?

AABBDD (2n = 6X = 42).

What are the three main species of wheat that make up 90% of wheat grown today?

Common or Bread wheat, Club Wheat, and Durum Wheat.

What is the primary use of Hard Red Winter Wheat?

To produce yeast breads, hard rolls, and all-purpose flour.

What is the primary growing region for Soft Red Winter Wheat?

East of the Mississippi River.

What is the main use of Durum wheat?

To make high-quality pasta.

What does vernalization refer to in wheat cultivation?

The induction of a plant's flowering process by exposure to prolonged cold.

What is the ideal soil pH for growing wheat?

6.0 - 7.0.

What temperature range is ideal for wheat growth?

55-75°F; hot weather over 95°F (35°C) can shock the crop.

What is the typical planting time for winter wheat?

From the fourth week of September to mid-October.

What are the major growth stages of wheat?

Germination, seedling growth, tillering, stem elongation, booting, ear emergence, flowering, milk development, dough development, and ripening.

What is the significance of the flag leaf in wheat?

It is the last leaf to emerge before the wheat head (spike).

What are the bristles on the wheat head called?

Awns.

What is a spikelet in wheat?

The basic unit of a wheat flower, consisting of at least three florets.

What is the role of the stigma in wheat flowers?

It is the female (pollen-receptor) part of the flower.

What is the primary use of Soft White Wheat?

For flat breads, cakes, pastries, and crackers.

What is the difference between Hard Red Spring Wheat and Hard Red Winter Wheat?

Hard Red Spring Wheat is used for designer breads and is grown in colder areas, while Hard Red Winter Wheat is planted in the fall and completes its life cycle in the spring.

What is the typical chromosome number for Club Wheat?

42 (2n).

What is the first stage of wheat growth?

Seedling growth

What occurs during germination?

The seed absorbs water and begins to sprout.

What is the significance of the coleoptile in wheat growth?

It is the first leaf that emerges from the seed.

What does 'tillering' refer to in wheat growth?

The development of additional shoots from the main stem.

What is the 'flag leaf' in wheat?

The last leaf to emerge, crucial for photosynthesis.

What happens during the 'booting' stage?

The flag leaf sheath extends and the ear begins to emerge.

What is the 'flowering' stage in wheat?

The period when the wheat plant begins to produce flowers.

What is 'milk development' in wheat?

A stage where the seed is filled with a milky substance.

What are the signs of 'ripening' in wheat?

Seeds become hard and difficult to dent with a thumbnail.

Name a broadleaf weed species that affects wheat.

Kochia

What is a common grass weed species in wheat?

Brome or 'cheatgrass'

What is the impact of the wheat stem sawfly?

It reduces vascular efficiency, leading to fewer kernels and lower weight.

What is the role of the wheat curl mite?

It transmits the wheat streak mosaic virus disease.

What is Fusarium head blight?

A serious disease of wheat characterized by tan lesions on spikelets.

What mycotoxin is associated with Fusarium head blight?

Deoxynivalenol (DON)

What does 'loose smut' do to wheat heads?

Replaces normal head tissue with dark masses of fungal spores.

What are the symptoms of bacterial streak in wheat?

Water-soaked areas between leaf veins that turn tan.

What viral disease causes yellow or red discoloration in wheat leaves?

Barley yellow dwarf virus

What is the key diagnostic feature of tan spot of wheat?

Tan lesions with a yellow margin.

What was the Barberry Eradication Program?

A program to remove common barberry, a host for stem rust disease.

What type of damage does the Hessian fly cause?

It can significantly reduce wheat yield.

What is the management strategy for powdery mildew in wheat?

Genetic resistance and foliar fungicides.

What is the appearance of wheat infected by loose smut?

Heads appear black and powdery due to fungal spores.

What is the impact of aphids on wheat?

They pierce and suck plant juices, weakening the plant.

What is the significance of the 'first spikelet' in wheat?

It indicates the beginning of ear emergence.

What does 'dough development' refer to?

The stage where seeds begin to harden and lose moisture.

What is the effect of the armyworm on wheat seedlings?

It damages seedlings, reducing their growth and yield.