Pomology

Pomology .. Producing, storing, processing, and marketing of fruits and nuts

More than half of fruits and nuts are produced for the fresh market. California, Florida, and Washington are the leading states producing fruits and California, Georgia, New Mexico, and Texas and leading nut producers.

Fruit Classification

Fruit .. Mature ovary of a flowering plant or tree that includes seeds, its covers, and any connected parts.

Seeds are fertilized ovules.

Simple fruit .. One from a flower with a single pistil

Aggregate fruit .. One from a single flower with several pistils (raspberries, blackberries, strawberries)

Multiple fruit .. One from flowers that are separated but closely clustered (pineapple)

Both fruits and nuts come from trees

Vegetables differ in that they are typically annuals

Nuts are indehiscent, single seeded fruits with a hard pericarp or shell.

Usage of Fruits and Nuts

Fruits and nuts contain important vitamins and minerals, are rich in phytochemicals, can trap dietary cholesterol, prevent colon cancer, and are high in antioxidants.

Dormancy

Fruit crops undergo two types of dormancy:

Endodormancy .. also known as rest, imposed by internal blocks in seeds and buds; regulated by hormones and overcome by winter chilling

Ectodormancy .. also known as quiescence, plant will not grow until external conditions are satisfied

Both work together to prevent bud break at the wrong time of year.

To overcome dormancy, a plant must reach the required number of chilling hours and then undergo the correct amount of heat units.

Plant Growth Regulators

Plant growth regulators are used to thin flowers, prevent fruit drop, induce abscission, and control ripening

Thinning of Fruit Crops

Thinning .. The removal of excess parts of a crop before it matures on a tree

Trees thin themselves, but chemical thinning is done by growers for a number of reasons

Thinning increases fruit size, promotes higher sugar content, increases fruit coloration, reduces limb breakage, reduces diseases and pests, and allows the alternation of bearing tendencies.

Chemical Thinning of Fruit Crops

Chemical thinning was commercialized in 1949. Growers will typically overthin to avoid having to go back and re-thin by hand.

Weather plays a role in thinning. Less thinning occurs in cooler and sunny weather, with the optimal temperature being in the 70s. Cloudy days before or after thinning are avoided.

There are numerous chemicals that can be used for thinning, including plant growth regulators.

Timing varies in chemical application. Waiting until after bloom to apply provides better weather and lets one evaluate fruit set.

Naphthaleneacetic acid (NAA) .. stimulates ethylene which slows development of youngest and weakest fruits, eventually abscising them; response of plant is proportional to amount applied; can cause flagging or phytotoxicity over 85 degrees.

Carbaryl .. safest means to thin as this almost never overthins; accidentally discovered to have thinning properties; an insecticide, and therefore toxic to honeybees

Harvesting

Crops are often harvested at peak color, flavor, and quality, but different markets can alter this. Peaches are picked when they are firm so they can be shipped long distance, for example.

Many fruits are picked mechanically, but large fruits are still picked by hand.

Ripening can be promoted with plant growth regulators or prevented by blocking ethylene biosynthesis and removing ethylene from the area post harvest.

Prevention of fruit drop is important in harvesting to prevent bruising, consumption of fruit by animals, and to keep the fruit sanitary. Plant growth regulators are used for this, but sometimes it works too well and ethrol must be applied to promote abscission, which has its own issues (leaf drop, reduction in future crops, decline in vigor).

When harvesting, heat should be removed from fruits as quickly as possible and they should be placed in cold storage.

Picked fruits are still living.

Other Uses of Plant Growth Regulators

Plant growth regulators can be used to increase fruit size (cytokinin and gibberellin), elongate fruit (gibberellin), and enhance color.

Entomology

Entomology .. branch of zoology concerned with the study of insects

Plant protection includes entomology, plant pathology, and weed science to name a few items

Insects typically lay eggs, but sometimes have live births. Sometimes no fertilization is needed.

3 main sections of an insect: head, thorax (behind the head), and abdomen. Insects have six legs, two pairs of wings, and one pair on antennae.

Metamorphosis .. changes in body shape and form.

Growth of an insect is limited by the exoskeleton. During metamorphosis the exoskeleton is replaced by a new one.

There are three different ways that insects go through metamorphosis and change

1. Hemimetabolous (Incomplete). Slight changes are undergone during metamorphosis.

2. Holometabolous (complete). Large changes are undergone, going from a worm-like larvae to an insect.

3. Ametabolous (no real change in insect).

50% of insect species feed on plants. there are more species of insects than all plants and other animals combined.

Many insect species are helpful to plants.

Some insect species are phytophageous and only eat plants

Coevolution frequently occurs between plants and insects, for example the monarch butterfly and milkweed.

Coevolution .. evolution of one trait of a species in response to a trait in another.

Phytophagous Insects

Phytophagous insect .. one that feeds exclusively on plants

Monophagous insect .. one that feeds on only one plant taxon

Oligophagous insect .. one that feeds on a few plant taxa

Polyphagous insect .. one that feeds on many plant groups

Most damage to plants through phytophagous insects comes from the feeding itself, although egg laying can also cause damage.

Understanding the mouthparts of insects helps us to assess damage and determine control methods.

Insects may be external or internal feeders and some may be both during their life cycle. External feeders are more exposed.

Mouthpart Types: Chewing

Chewing mouthparts are the least specialized mouthparts. Mandibles move in a scissoring motion. Chewing mouthparts can cut holes and eat organs of plants.

Damage from chewing mouthparts can be identified using frass that is visible near the area.

Mouthpart Types: Piercing-Sucking

Piercing-sucking mouthparts are used to penetrate plants and suck their sap.

Damage from piercing-sucking mouthparts can be identified through honeydew left on the leaves. It may cause black sooty mold growth and attract ants.

Mouthpart Types: Rasping-Sucking Mouthparts

Rasping-sucking mouthparts are only found in thrips. They can scape and suck.

Root Damage

Root damage is caused by piercing-sucking or chewing mouthparts. Symptoms include wilting, yellowing, and thinning out of plants.

Stem Damage

Stem damage is cause by piercing-sucking or chewing mouthparts in addition to ovipositors.

Stem damage may be caused by borers.

Symptoms of stem damage include galls.

Stem Damage: Galls

Galls .. tumor-like growths of plant tissues that can stunt or kill portions of a stem and provide a protective environment for an insect.

Stem Damage: Borers

Borers may tunnel in roots and/or stems, typically in the larval stage. This disrupts the vascular tissues. Sawdust is commonly found.

Leaf Damage

Leaves may be abscised, eaten, or tunneled through and may show galls, spots, or damage. Cabbage worm typically eats leaves.

Many larvae are leaf miners.

Leaf Damage: Leaf Miners

Larval forms of sawflies, moths, and flies have chewing mouthparts and bore or tunnel into leaves, ingesting internal leaf cells. This reduces photosynthesis and may make ornamental plants unmarketable. The easiest time to control these insects are when they are outside the leaves, in the egg stage.

Fruit or Flower Damage

Flower damage is often from thrips or general feeding.

Fruit damage is usually from ovipositors or feeding.

Important Insect Orders to Know for Horticulture

• Collembola (springtails)

  • Collembola (insect order) .. springtails, nuisance on ornamentals and mushrooms

• Orthoptera (grasshoppers)

  • Chewing mouthparts

  • Orthoptera (insect order) .. grasshoppers and mole crickets, feed on perennial plants and cause turf damage

• Thysanoptera (thrips)

  • Rasping-sucking mouthparts

  • Thysanoptera (insect order) .. thrips, a major problem in greenhouse crops, major issue is disease transmission

• Hemiptera (bugs): Broken into two orders (won’t be broken up in the exam)

  • Heteroptera (insect order) .. true bugs that can discolor or disfigure leaves

  • Homoptera (insect order) .. aphids and scale insects known for leaving honeydew behind

• Coleoptera (beetles)

  • Chewing mouthparts

  • Coleoptera (insect order) .. beetles which can be borers; adults and larvae have chewing mouthparts

• Diptera (flies)

  • Chewing or piercing-sucking mouthparts

  • Diptera (insect order) .. true flies

• Lepidoptera (butterflies)

  • Chewing mouthparts (larvae)

  • Lepidoptera (insect order) .. butterflies, adults do not harm plants

• Hymenoptera (wasps)

  • Chewing mouthparts

  • Hymenoptera (insect order) .. wasps and sawflies; have chewing mouthparts

Greenhouses

Greenhouses were first used in Ancient Rome to protect tender crops and allow for a controlled environment. Greenhouses are used today for fruits, vegetables, and ornamentals.

Headhouse: Central greenhouse building for offices, storage, and workbenches

Greenhouse: Glass structure

Attached greenhouse: one attached on an existing structure; must be located on the south side of the building.

Detached greenhouse: separate from other buildings where the environment is easily regulated

Connected greenhouse: several joined together

Detached Greenhouses

There are four types of detached greenhouses

Even span is the most common, with an equal pitch and width.

Connected Greenhouses

There are different ways that greenhouses may be connected, but snow and ice can be an issue regardless of the type of connection.

Greenhouse Coverings

Greenhouse coverings are used to allow maximum amount of light into the greenhouse. No material can transmit 100% of light.

Glass

Glass coverings transmit about 90% of light. Different types of glass can be used to reduce light intensity, and glass tends to filter out UV light. Constructing glass greenhouses is expensive, as is the maintenance and operation. Glass also breaks easily and can present safety issues when this occurs.

Plastic Film

Many types of plastic films can be used. They are less expensive and more energy efficient, but they have shorter lifespans.

Fiberglass

Fiberglass is a reinforced plastic covering which allows the came transmission as glass. Fiberglass also disperses light in a way that glass does not. Fiberglass is susceptible to degradation to UV light and is flammable.

Acrylic and Polycarbonate

Acrylic and polycarbonate are very expensive but can last up to 25 years (longest lasting other than glass). They are good for light transmission and heat insulation, but are flammable.

Orientation

Greenhouses should be oriented to maximize the amount of sunlight and minimize heat loss through wind.

Benches

Benches should maximize space and accessibility to plants on those benches.

Heating Systems

Steam: Water at 215F is piped throughout the greenhouses; efficient for large greenhouses

Hot water: Used in small greenhouses for heating, but is inefficient for larger ones

Forced air: Unit heaters force air through the greenhouse, prone to drying out the air

Infrared radiant: Warms objects more than the air

It is expensive to heat a greenhouse.

Cooling

The greenhouse effect heats the greenhouse through the sun. Greenhouses can be cooled in a number of ways:

• Roof vents allow heat out through the top of the greenhouse, but may allow pests in

• Exhaust fans pull air through the greenhouse to circulate the air

• Air conditioning

• Evaporative cooling systems: Fan and pan method where water flows through pads and air is pulled through the pads. Warm air is taken out through fans

• White wash coating applied to glass

Acarology

Acarology: the study of mites and ticks

All ticks are mites but not all mites are ticks. Chiggers are also included in this.

Biology

Mites have two body regions and four pairs of legs

Most mites have the ability to bite and chew.

Mites

Pesticide resistance develops quickly in mites.

High levels of inbreeding occurs in mites.

Unmated females produce male mites, which are haploid. Mated females produce females, which are diploid.

Spider Mites

Spider mites reproduce fast in warm, dry conditions. They are especially problematic in dusty areas such as Mediterranean climates.

Spider mites produce silk to protect from predators, desiccation, and pesticides.