Pecan anthracnose

Key takeaways

Pecan anthracnose belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Pecan anthracnose to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Pecan anthracnose from memory before moving on to harder problems.

Reference excerpt

Pecan anthracnose is a fungal disease of pecan trees caused by the ascomycete Glomerella cingulata (Stoneman) Spauld. & H. It is a widespread disease found wherever pecan trees are grown. Pecan anthracnose has been reported as far back in time as 1914 (Rand 1914), and as far away as Argentina (Mantz, Minhot et al. 2010). Glomerella cingulata has two anamorphs which cause disease on pecan trees, Colletotrichum gloeosporioides and Colletotrichum acutatum (Latham 1995). The occurrence of Colletotrichum on pecans has contributed to a significant decline in pecan production in various years. An increase in the incidence of pecan anthracnose is highly correlated with heavy rainfall, especially heavy rainfall occurring in early spring. The severity of symptoms increases as the season progresses, often culminating in leaf drop in the late autumn. This defoliation is linked to lower yield and poorer quality of nuts (Brenneman 2010).

Overview of disease Pecan anthracnose is caused by the fungus Glomerella cingulata and is a disease of pecan trees that causes significant losses of yields as it attacks the nut itself. Pecan anthracnose is favored by wet environmental conditions and warm temperatures above 80 degrees Fahrenheit. Symptoms include dark lesions on the pecan shuck and leaves. The lesions can grow over the entire plant. Signs include pink spores inside of the lesions. If left untreated, symptoms will get progressively worse throughout the season, progressively reducing yield. Pecans are primarily grown in the southern part of the United States, so these warm, wet areas are most susceptible to pecan anthracnose. Pecan anthracnose can occasionally cause zinc deficiencies in the trees it infects; of the cultivars of pecans that are susceptible, Witchita, Kiowa, Gloria Grande, Pawnee and Mohawk are most prone to zinc deficiencies. Pecan anthracnose can significantly cost farmers; the disease causes infected trees to produce less nuts and or drop them too early. Additionally, like mentioned above, the lesions of the disease can grow to cover the entirety of a fruit, making the pecan crop unsellable and unconsumable. It is estimated that pecan anthracnose cost Georgia farmers 3.4 million dollars in 2009.

Prevention and control For pecan anthracnose, it is best to use a similar control method to that used against pecan scab. Both pecan scab and anthracnose are best controlled by making sure the plants get plenty of airflow to keep their environment dry (one way to do this is by making sure the plants are not crowded together). Additionally, it is important to remove the dead leaves, nuts, etc. from the past season because the pathogen can overwinter in these structures and strike again the following year). Another form of control involves spraying fungicide 7–12 times throughout the season, beginning in the spring. As a preventative measure it is important to spray fungicide as soon as the bud breaks. Spraying fungicide also helps to ward off powdery mildew and pecan scab. In 2012, it was found that compounds created from Lactobacillus plantarum had important antifungal properties that could be used to treat pecan anthracnose caused by Glomerella cingulate. As far as prevention goes, there are some varieties of pecan plants that are resistant to anthracnose and pruning out and destroying diseased plants can help to stop the spread of the disease.

Life cycle Pecan anthracnose is an ascomycete fungus and has a life cycle similar to that of other ascomycetes. Anthracnose has an overwintering stage and survives as an ascocarp. The ascocarp can survive on fallen nuts, leaves and other plant debris. Ascocarps can be spread by the wind or rain. Then, during a rainy, warm spring or summer, the ascocarp releases its ascospores and they go off and infect new plants to create more ascocarps which in turn make more ascospores and the life cycle begins again. Anthracnose is polycyclic, so it has a sexual stage as conidia when it finds its mating type.

Economic consequences The financial loss due to pecan anthracnose in 2009 in Georgia was estimated at US$3.4 million (Brock 2010). However, the actual loss due to the disease is difficult to quantify. Due to the nature of carbohydrate storage in perennials, the damage to pecan production is also likely to present itself in a lower yield in the year directly following a disease outbreak (Worley 1979).

Progression of disease Pecan anthracnose is reported to have an unusually long latent period; it can take weeks to months from the time of initial infection to symptom development. Both ascospores and conidia can be found in the field and in culture, and both of these spore types can cause infection (Rand 1914).

Symptoms Pink conidial oozes can be observed emerging from acervuli with setae on leaves and shucks.

Worked examples

Example 1 — a first encounter with Pecan anthracnose

Start with the simplest possible case. Write down what Pecan anthracnose claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Pecan anthracnose before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Pecan anthracnose ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Pecan anthracnose

In research: Pecan anthracnose appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Pecan anthracnose in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Pecan anthracnose is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fungal diseases, Pecan tree diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Pecan anthracnose outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Pecan anthracnose in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pecan anthracnose means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Pecan anthracnose out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pecan anthracnose in simple terms?

Pecan anthracnose is a fungal disease of pecan trees caused by the ascomycete Glomerella cingulata (Stoneman) Spauld. & H. It is a widespread disease found wherever pecan trees are grown.

Why does Pecan anthracnose matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Pecan anthracnose?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Pecan anthracnose.