Destruction of seedlings near the soil line, resulting in the seedlings falling over on the ground

Individual strands of a mass of mycelium

A conidium-bearing fruiting structure associated with many anthracnose diseases

A protein produced by living cells that can catalyze a specific organic reaction

Having one cycle per season

Completes many (life or disease) cycles in one year

Rust spore stages

Teliospore

The sexual, thick-walled resting spore and smut fungi

Rust spore stages

Basidiospore

A sexually produced spore borne on a basidium

Rust spore stages

Spermatia

The male gamete or gametangium of rust fungi

Rust spore stages

Aeciospores

Rust spore stages

Urediospores

Which also infect and produce either more uredia and uredospores or, near host maturity, telia and teliospores

A disease caused by a smut fungi (Ustilaginales) characterized by masses of dark, powdery and sometimes odorous spores.

Generally microscopic, worm-like animals that live saprophytically in water or soil, or as parasites of plants and animals

1. Rhabditida (buccal cavity)
2. Dorylaimida (odontostylets)
3. Tylenchida (stomatostylets)

1. Saprophyte
2. Parasite

Are hollow spears associated with tylenchoids

Are solid, tooth-like structure associated with dorylaims

• Stomatostylet
• Endoparasite
• Prefers high temps
• Mature female is pear-shaped
• lays eggs externally
• Galls due to growth regulators/"giant" cells

• Stomatostylet
• Endoparasite
• Relatively narrow host range
• Mature females are lemon-shaped
• lays eggs within bodies
• readily recognized on roots (pear-like females)

• Stomatostylet
• Endoparasite
• Causes langular lesions on leaves

• Odontostylet
• Ectoparasite
• wide host range
• transmits certain viruses, including (corky ringspot)
• impedes root tip development
• Dorylaims in the genus Trichodorus transmit the tobravirus, tobacco rattle, which commonly infects potatoes, causing "corky ringspot" in Hastings, Florida

He is known as the "father of modern genetics", was inspired by both his professors at University and his collegues at the monestary to study variation in plants

Between 1856 and 1863, he cultivated and tested some 29,000 pea plants

This study showed that one in four pea plants had purebred recessive alleles, two out of four were hybrid and one out of four were purebred dominant.

His experiments brought forth two generalizations

• The Law of Segregation
• The Law of Independent Assortment

These late became know as                   laws of inheritance

A fungal disease of plants in which the mycelium and spores of the fungus are seen as a whitish growth on the host surface

1. Eriophyids
2. Tetranychids
3. Tarsonemids

Wall-less mycoplasma-like bodies in the phloem of plants exhibiting yellows and witchs' broom symptoms.

Diseases caused by mollicutes appear as stunting of plants, yellowing or reddening of leaves, proliferation of shoots and roots, production of abnormal flowers, and eventual decline and death of plant

The hypha or mass of hyphae that make up the body of a fungus

• Source: Automobile exhausts and other internal combustion engines (released NO2 combines with O2 in sunlight to from O3). From stratosphere. From lightning, from forests
• Susceptible plants: expanding leaves of all plants, especially tobacco, bean, cereals, alfalfa, petunia, pine, citrus, and corn
• Symptoms: Stippling, mottling, and chlorosis of leaves, primarily on upper surface. Spots are small to large, bleached white to tan, brown, or black
• Remarks: Enters through stomata. It is the most destructive air pollutant to plants. A major component of smog

• (high cash value prohibitive for all but the most expensive crops, usually ornamentals; however use is limited because of expense.
• Tissue culture of disease-resistant plants is particularly useful with clonally propagated plants such as strawberries, apples, bananas, sugar cane, cassava, and potatoes

• (infects only once)

• The overwintering or oversummering pathogen, or its spores that cause primary infection

• Is a stage in the sexual reproduction of fungi.
• In this stage, the cytoplasm of two parent mycelia fuse together without the fusion of nuclei, as occurs in higher terrestrial fungi
• After plasmogamy occurs, the secondary mycelium forms. The secondary mycelium consists of dikaryotic cells, one nuclues from each of the parent mycelia

Control of import and export of plants to prevent spread of diseases and pests

(infects more than once) inoculum produced by infections that take place during the same growing season

a compact mass of spores or fruiting structure found especially in rusts and smuts

• Is caused by the Basidiomycete fungus Phakopsora pachyrhiza

• Leaves with tan and reddish brown lesions as they appear macroscopically in the field

is known today as ergotism and is the result of people and animals consuming grain coming from cultivated cereals and wild grasses infected with one or several ergot producing fungi.

Ergot (from the French "argot," which means a spur)

is the fruting structure produced by Claviceps purpurea and related fungi in place of the plant and contaminates the grain after harvest

the sexual, thick walled resting spore of rust and smut fungi

• Is a circular plasmid that often, but not always, is a part of the genetic equipment that Agrobacterium tumefaciens and Agrobacterium rhizogenes use to transduce its genetic material to plants.

• The                  is lost when Agrobacterium is grown above 28C

Nuclear Conditions

Basidiomycete

All rusts are basidiomycetes

Dikaryotic mycelium 1N+1N i.e. plasmogamy not karyogamy

Nuclear Conditions

Ascomycete (and most Deuteromycete)

Nuclear Conditions

Zygomycetes

Nuclear Conditions

Oomycetes

• Many plant viruses, such as cucumber mosaic virus, are brought into crops, such as peppers, by airborne aphid vectors. If reflectant aluminum or black, whitish-gray, or colored polyethylene sheets are used as mulches between the plant rows in the field, incoming aphids, thrips, and possibly other insect vectors are repelled and misled away from the field.
• As a result, fewer virus-carrying vectors land on the plants and fewer plants become infected with the virus

• Normally, monsoons begin the 3rd week in June, becomes incessant July-August, and tails off towards the end of September.
• November through December are rainless, humidity is low, and there are many "bright sunshine hours"

The bengal famine of 1942,

• Unusually heavy rainfall in Sept.
• Unusual and prolonged cloudy weather in Nov. with very low "Sunshine hours" and occasional rains
• Higher minimum temps

A plant disease in which the sporangiophores and spores of a fungus appear as a downy growth on the lower surface of leaves and stems, fruit, etc., caused by fungi in the family Peronosporaceae

• Mostly cool or warm, but not hot conditions
• Mostly Oomycetes

Food Origins

Rice

Food Origins

Wheat

Food Origins

Corn

Food Origins

Potatoes

The best known of the Ergot alkaloids is lysergic acid diethylamide, the infamous LSD that was widely used as a hallucinogen by the hippie culture of the 1960's.

Depending on weather, the host plant (wheat, rye, barley, etc.) and the species of the ergot-forming fungus, the amount of ergot in the field and in the harvested grain may vary, as does the frequency and severity of the symptoms of ergotism

• Ascomycete
• Prefer dry weather (worst out west) spores do not germinate in free water

Rust

Autoecious

Rusts

Monoecious

• (rusts only having one home) that is plants have separate male and female flowers on the same plant.
• A plant population where the male and female organs are found in different flowers on the same plant

Rusts

Macrocyclic

• (long-cycled) means it has all the stages.
• In addition to teliospores and basidiospores, spermatia (formerly known as pycniospores), aeciospores, and uredospores (also known as urediospores or urediniospores in that order)

Rusts

Microcyclic

• The inability of a pathogen to infect a certain plant variety that carries genetic resistance
• The avr genes make a pathogen avirulent, that is unable to induce disease on a specific variety of the host plant because their protein product warns the plant of impending attack by the pathogen and the host plant then mobilizes its defenses and blocks infection by the pathogen.
• Avr protein: the protein coded for an avr gene, acting as an elicitor of defense reactions

Nonliving, or caused by a nonliving agent

Examples: excess light, air pollution (ozone and acid rain), herbicide injury, Nutritional problems, physical damage (invertebrates- certain suctorial insects causing "hopper burn, galls. Also, damage caused vy Eriophyid and broad mites.

• A subdermal, saucer shaped, asexual fruiting body producing conidia on short conidiophores
• A flat, open pad of short conidiophores growing side-by-side
• The conidiophores develop from the underlying mass of somatic hyphae

• These bacteria are rhizosphere and soil inhabitants
• involves introducing T-DNA from its plasmid that induces a tumor (Ti-Tumor inducing gene) into the plant cell, and is hence termed "genetic recombination."
• Discovered in 1890 by Erwin Smith

• Deuteromycete
• Induces zonate lesions
• Early blight, wide host ranges
• can be controlled with UV absorbing film, in greenhouses (preventing sporolation)

• Colletotrichum, Gloeosporium (Deuteromycetes) result in open basin-like sores
• The above two genera are Anamorphs (asexual), and most commonly encountered among the anthracnose fungi
• Teliomorphs (sexual) are less common (Glomerella, perithecium)
• Primary cycle involves conidia and plant debris

Kingdom Planta

Any flowering plant; plants that produce seeds enclosed within a carpel (a carpel is the ovuliferous organ of the flower; a simple pistil or one of the segments of a compound pistil. (ovary, style, stigma)

Oomycete (Chromistic algae)

• Seedling disease (Root Rot)
• In new seedlings, symptoms often appear in the form of stunted, yellow plants with overall poor root development and few lateral roots
• Most severe in wet conditions

A meristem (growing region) at the tip of a plant shoot or root that produces auxin and causes the shoot or root to increase in length.

Growth that originates in the apical meristem is called primary growth. (this area is free of viruses (not present), allowing for tissue propagation, but very expensive.)

•                curve will result in three important points on a graph

1. Lag Phase
2. Exponential Phase or logarithmic phase
3. Deceleration phase

Produces aflatoxin, a deadly carcinogen. Favors dry conditions

In peanuts, dry conditions result in peanuts cracking (outer shell), and provides a pathway for the pathogen to enter.

Similar to Penicillium spp. but Penicillium are blue-green, deuteromycetes, this prevails (mold and blue cheese)

• Researcher isolated and identified new types of bacteria from soil, particularly autotrophic bacteria, that use inorganic chemicals as nutrients and as a source of energy.
• The earliest indications of the biological nature of viruses came from studies in 1898 by this Dutch scientist                  .
• Considered founder of virology
• Termed viruses as a "contagious living fluid"

Caused by Helminthiosporium oryzae (brown spot of rice), 1942 and 1943. Cool, wet conditions were present during disease outbreak.

The crop was ruined and the result was widespread famine.

Longer rain period with less sunshine

Over 2 million people died because of this.

Sexual stage with filamentous ascospores

• Bipolaris (formerly Helminthosporium) maidis (Deuteromycete name) - "Southern corn leaf blight" Anamophic, affected kernels are covered with black, felty mold, and cobs may rot or, if the shank is infected early, the ear may be killed prematurely and drop
• Cochliobolus heterostrophus (ascomycete name) (teliomorph)

Gray mold

Deuteromycete

• Most common disease of greenhouse crops and elsewhere
• Favors cool, humid conditions, gains ingress thru injury thru decaying flower petals or damaged leaves and then advances towards healthy tissues.
• Produces gray mycelium, conidia, and FLAT sclerotia

• Not a true vascular wilt, rather it girdles the bark of its host instead
• Overwinters in the host tissue, during growing season, suckers are produced, but they subsequently become infected and die back
• Fungus eats vascular tissues

"closed like a vase," "Tomb-like" circular structure=black ball. Some have hook-like structures around the "ball," while others have "myceloid appendages."

Produced by the sexual stage of powdery mildews (Oidium-asexual), Phyllactinia- is the teleomorph

The structure houses ascospores

• Deuteromycete
• Many species, many hosts, both dicots and monocots
• Lesions often have dark borders and tan centers
• Unique conidia shape

• Ergot- cannot be eaten, derivative is LSD, this is thought to be a symbiotic relationship, bacause it prevents herbivory
• Ascospores are filamentous (more surface area), spores are shot out, copper supplements reduce the incidence of the pathogen
• Copper deficient soils allow for flowers to remain open longer (greater pathogen window)

• Unique sporangium (modified), with spores solitary on structure. Do not confuse with Oomycota, it is actually Zygomycota.
• Coenocytic mycelia (male and female reproductive structures), virtually indistinguishable from each other (verses Oomycota male: antheridium, and female oogonium).
• The mycelia produce a zygospore, when male and female mycelia come together. (Undergoes plasmogamy and karyogamy) (do not confuse this with zoosporangium (Oomycota) which contains zygospores (flagellate spores))

• Phytoplasmas are pleomorphic, meaning "malformed looking."
• Lack cell walls and are susceptible to tetracycline

• Coffee is Ethiopian in origin, with its worst occurrence of disease in Sri Lanka.
• Probably classified as microcyclic (not all cycles of rust life cycle are present) vs. macrocyclic (wheat rust- they have all the stages)
• presumed heteroecious (two homes)
• caused the english to become tea drinkers

• Deuteromycete
• An anthracnose disease
• Can be determined by the presence of hairs around the acervulus. Open basin-like sores=symptoms.
• Signs= acervuli with spores
• Anamorphs are the most common (Colletotrichum/Gloesporium)
• An asexual form of perithecium (sexual fruiting structure), is a pycnidium which contains conidia versus the perithecium which contains ascospores (both are "flask-shaped")

Corn Smut

Basidiomycetes (restricted to the poaceae-affecting the grains)

• Basidiomycetes
• Very unique (smuts in general)
• Teliospores, 2n (nuclear condition), germinate to for basidia)
• Basidia form basidiaspores, which are 1n
• The basidiospores that infect the host are 1n
• Hyphal anastomoses results in a union of 1n+1n
• Galls form, mycelium occupies hyperplastic cells

• attacks particularly slash and loblolly pine; however, disease does not spread from pine to pine
• Oaks are equivalent of wheat (wheat rust life cycle)
• Pines are equivalent to barberry
• One cycle a year due to the presence or non-presence of juvenile tissues (needed to infect). Causes malformed protuberances (galls) on the pines

Disease control principles

Exclusion

• relates to the pathogen-keep it away (Quarantine-citrus canker story, coconut lethal yellowing, Dutch elm disease- realize the points of the examples
• Separate growing areas (seedling/adult), grow where pathogen cannot survive.
• Use certified seed

Disease Control Principles

Eradication

relates to the pathogen-- eliminate the pathogen if it enters the area.

Methods:

1. Rouging (pulling up infected plants, and allow them to die)
2. Eliminate alternative hosts (rusts)
3. Crop rotation
4. sanitation

• Biological Control (trap crops, parasitism)
• Physical control (heating the soil, cooling your product (cut flowers)
• Chemical control for pathogens

Disease Control Principles

Protection

Disease control principles

Genetic Resistance

• This pathogen managed to get to America (despite quarantine) on Bark-covered wood used as lumber
• The fungus overwinters in the beetle galleries, and when the beetles emerge, they spread the pathogen throughout their galleries
• True vascular wilt
• Vascular wilt pathogens primarily infect the XYLEM
• Scolytis multistriatus- the introduced beetle vector
• Cut off the wood, deprive the fungus. the beetle attack dead wood

• Is an example of a mycotoxicosis caused by food and feed made extremely unhealthy by mycotoxins.
• Several mycotoxins are proven carcinogens, may disrupt the immune system, and may retard the growth of humans or animals that consume them
• Causes vasoconstriction, and can result in limbs being removed/dying

• It is a rod-shaped bacterium, has peritrichous flagella, and requires nicotinic acid as a growth factor. Serological tests help identify it
• Ants help the initial dissemination (ants are present all around the tree) (ooze is sweet and sticky) where it is subsequently taken up by bees,who pass it to uninfected trees/plants by flower-to-flower movement.
• Focus on ooze, remove dead branches. Bees spread it exponentially. Sanitation

• vascular disease
• Sign is ooze
• Survives only a few weeks in infected plant debris. However, it survives over winter in the intestines of striped cucumber beetles, and spotted cucumber beetles, in which it hibernates

Bahavior is similar to Taphrina deformans (Peach Leaf Curl), and is virtually indistinguishable in accordance to symptoms and signs

• It is a basidiomycete VERSUS T. deformans an ascomycete
• Both require juvenile tissues, more prevalent in northern climates, because juvenile tissue is present much longer
• Both are monocyclic
• Leaves show bright red/green "curls"

• Ascomycetes (when sexual)
• Anamorph
• fusarium wilts (vascular wilts)
• species specific as noted by "forma specialis."
• narrow host range

• Ascomycetes (when sexual)
• wide host range
• "damping-off"
• (asexual stages=macroconidia, microconidia, chlamydospores)
• macroconidia contain chlamydospores (single-celled conidia with thick covering)
• Microconidia are solitary conidia
• Purplish mycelium

In mathematics it is also known as a geometric sequence, is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed non-zero number called the common ratio.

For example, the sequence 2,6,18,54... is a geometric progression with a common ratio of 3. Similarly 10, 5, 2.5, 1.25,... is a geometric sequence with common ratio of 1/2. The sum of the terms of a geometric progression is known as a geometric series.

• Compare with Colletotrichum.
• BOTH are anthracnose diseases, Gloeosporium lacks the hairs present around the acervulis, which is an indicator of Colletotrichum (hairs)
• Both are anamorphs

• Sexual stage is termed "saprophyte"
• While anamorphic stage (parasite-like) is much less effective in its spread (an ooze ermerges from the pycnidium to disperse conidia)
• The sexual stage disperses ascospores (perithecium) by "shooting them out"
• Much more effective

The fusion of 2 (usually haploid) nuclei during sexual reproduction, resulting in the formation of a diploid zygote.

This occurs immediately after plasmogamy  (the fusion of cytoplasm between two cells, usually gametes or protoplasts. Plasmogamy occurs shortly before karyogamy.)

• Not a true alternate host, but it enables Soybean rust (Asian soybean rust, Phakopsora pachrhizi) to persist throughout the winter in the southern United States.
•               cannot survive cold winters, but it is good at hiding.
•               was originally imported as a high protein forage food, but since it has become a very noxious weed.
• Some              show immunity, resistance, and no-resistance.
• Immunity and resistance may not always be present in                  , because of changes in the pathogen may negate immunity/resistance.

• Symptoms- moist soft rots, decay
• Signs- Sporodochia with conidiam apothecia, mummies
• Life Cycles- Primary (one): perithecia with asci

Secondary (many): sporodochia with conidia (especially fruits)

• Transition: Fruits mummify into a sclerotium-like structure

• Anamorphs
• Powdery mildews (Ascomycetes)
• Hyphae superficial, send haustoria into epidermis, but do not penetrate host further.
• Conidia are secondary inocula

Blue and Green molds

Deuteromycete

Signs: usually blue or green colored mycelium

Myxomycete, a protozoan plant pathogen

Causes clubroot; the causal agent is an obligate parasite

• Symptoms: are conspicuous root gall, no necrosis
• Very restricted host range
• Produces intracellular plasmodium
• Plasmodium breaks up into zoospores
• Require acidic soils; can be controlled by raising pH to about 7.2 or higher

• Downy mildew of grape
• Oomycete

• causing severe and often catastrophic diseases on numerous hosts such as the (stem rust of wheat and all other small grains)
• Also causes rust diseases on field crops such as cotton

Oomycete (Chromistic algae)

Symptoms: Below ground (root rot, stem cankers)

Above ground (stem cankers, foliar blights)

Signs: hyphae/mycelium (coenocytic)

Zoospores/sporangia

Sexual stage common: Oospores, Oogonia, Antheridia

• Southern bacterial wilt
• Vascular wilt caused by bacteria
• Mosty tropical
• Survives in plant debris, tubers, wild hosts

Basidiomycetes

Wide host range

Symptoms: below ground (root rot, stem cankers)

Above ground (stem cankers, foliar blights)

Signs: Hyphae/Mycelium (no spores, septate)

No asexual spores

sclerotia

Sexual stage not common

• Zygomycete molds or bread molds 
• Zygomycete
• Signs: rank, translucent mycelium with black sporangia

Cotton rot

Ascomycete

Associated with St. Andrew's Fire

Signs: white colored mycelium with "rat-turd" sclerotia

Most aggressive under cool, moist conditions

Sclerotinia sclerotiorum

Compare and Contrast

1. Rhizoctonia solani and Sclerotium rolfsii (sclerotia are formed, but no conidia)
2. Monilinia fructicola (apothecia are produced)
3. Opposite of Sclerotium rolfsii in that it thrives in cold weather

• (like Rhizoctonia)
• Deuteromycete
• Very wide host range
• Mycelium white (no 90 degree branching)
• Truly a hot weather pathogen
• Asexual stage without spores
• Sexual stage (Basidiomycete)

• A fungal leaf spot and very devastating
• Precludes consolidation plantings of rubber trees in Amazonia
• Consolidated planting of rubber trees is successful in Southeast Asia due to effective quarantine practices

Causes peach leaf curl

• Ascomycete
• Brightly colored, rubbery galls; no necrosis
• No ascocarp
• Requires juvenile tissues, abetted by cool weather

Tobacco rattle virus

• ssRNA, bi-partite, rigid rod
• Nematode-transmitted (the dorylaim, trichodorus)
• Very wide host range

Corn Smut

Mexican tacos

Teliospores (2N) germinate to form basidia

Basidia from basidiospores (1N)

Basidiospores infect hosts (1N)

Hyphal anastomoses results in (1N+N)

Apple scab

Symptoms: dry lesions

Signs: acervuli with spores

Life cycles: primary (one) Perithecia with asci (2-celled ascospores/disease forecasting)

Secondary (many): Acervuli with conidia

Transition: parasite become saprophyte

causes wilt in cotton

• Attack hundreds of kinds of plants, causing wilts and losses of varying severity
• All vascular wilts have certain characteristics in common
• The leaves of infected plants or of parts of infected plants lost turgidity, become flaccid and lighter green to greenish yellow, droop, and finally wilt, turn yellow then, brown, and die

• is one of the most feared of citrus diseases affecting all types of important citrus crops.
• It causes necrotic lesions on fruit, leaves, and twigs.
• Losses are caused by reduced fruit quality and quantity and premature fruit drop.
• The disease is endemic in Japan and Southeast Asia, from where it has spread to all other citrus producing continents except Europe.

• Citrus spot
• results in raised lesions, and was not particulary damaging

• This was produced by Sclerotium sclerotinium (oxalate acid)
• Oxalates deficient fungi were slower to infect, but still caused infection, showing that multiple chemical routes of infection may be present when dealing with this pathogen.
• A suite of enzymes with the ability to degrade the cell wall of its host

Resistance

Vertical Transmission

Resistance

Horizontal Transmission

This involves taking the current crop and finding a different species that shows no vulnerability to the pathogen and cross breeding them.

The resultant progeny would be isolated and evaluated for the gene that allows for resistance. This progeny (F1) would be bred back into the original susceptible line, and they would evaluate for gene transfer to their progeny (original strain + F1 cross).

Bipolaris (formerly Helminthosporium) maidis (Deuteromycete name)

Cochliobolus heterostrophus (Ascomycete name)

• Sexual stage a perithecium with filamentous ascospores
• Genetic recombination led to 1970's blight epidemic