Cranberry fruit rot (CFR) is a disease complex of multiple fungal agents affecting the American cranberry (Vaccinium macrocarpon). Cranberry fruit rot can be categorized into field rot (rot occurring while growing and before harvest) and storage rot (occurring any time after harvest). [1] The importance of field rot and fruit rot depends on how the cranberries will be processed after harvest. If cranberries are immediately processed after harvest, growers focus on preventing field rot while with fresh market cranberries, growers seek to prevent storage rot. [1] There are 10-15 fungal pathogens known to cause cranberry fruit rot diseases, some active in only field rot, storage rot, or both. [2] The majority of these fungal pathogens are ascomycetes, with the rest being deuteromycetes. [2] There is no known bacterial pathogen that plays a role in CFR or any major disease on cranberry, potentially due to the low pH conditions on the cranberry fruit. [3]
In cranberries, the fruit rot pathogens can infect before or after harvest. The symptoms of rot are related to a general softening and deterioration of the cranberry, which occur both in the field and in storage. [1] Each specific rot disease that makes up the CFR disease complex is caused by specific pathogens (Table 1). An example is the field rot cotton ball caused by Monilinia oxycocci , common in Wisconsin, while bitter rot caused by Glomerella cingulate generally occurs in Massachusetts. [4] However, these pathogens have been shown to not be entirely specific to their areas. [5] These symptoms can often resemble other forms of fruit deterioration such as sunscald, hail damage, and temporal physiological breakdown. [1]
Disease | Fungus | Field Rot | Storage Rot |
---|---|---|---|
bitter rot | Colletotrichum acutatum | X | |
cottonball rot | Monilinia oxycocci | X | |
early rot | Phyllosticta vaccinii | X | |
berry speckle | Phyllosticta elongata | X | X |
blotch rot | Physalospora vaccinii | X | X |
end rot | Fusicoccum putrefaciens | X | X |
ripe rot | Coleophoma empetr | X | X |
viscid rot | Phomopsis vaccinii | X | X |
yellow rot | Botrytis sp. | X | X |
black rot | Allantophomopsis lycopodina | X |
Due to the complexity and number of fungal pathogens involved in CFR, the specific disease cycles have yet to be fully studied. Researchers believe almost every fruit rot pathogen completes a disease cycle every 1–3 years. [2] Researchers however have hypothesized 3 potential disease cycles taken by the pathogens. [1] These 3 disease cycles rely heavily on leaves or stems, either debris or living, mainly because all berries are harvested. [1]
The management of CFR can be complicated and varies due to the number of pathogens and the temporal aspect of fruit rot. Fungicides applied during the projected times of infection and on potential areas, such as flowers and after fruit set, are effective at deterring fruit rot. Due to the number of pathogens, general fungicides such as chlorothalonil, instead of specific-targeting fungicides, are more effective. [2] However, fungicides can reduce fruit quality and fruit set in some cases, thus their use is often limited. [2] Harvest can also play a role in reducing the risk of pathogens. Wet harvest using floodwater, although quicker and easier, can spread pathogens, which would increase chances of storage rot. [6] Dry harvests can cause more damage to vines and take longer, but can reduce disease spread and decrease the potential of storage rot. [6] Depending on the final use of cranberries, each harvest type can be beneficial. Sanding, a process where sand is laid on the field to stimulate root growth from the harvested cranberries, could actually play a role in covering up inoculum with plant debris, which may decrease the chances of field and storage rot. [2] Resistance and biological controls have proved difficult to validate due to the disease complex being composed of different fungal pathogens. [2]
Botrytis cinerea is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or "gray mold".
Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.
Phomopsis cane and leaf spot occurs wherever grapes are grown. Phomopsis cane and leaf spot is more severe in grape-growing regions characterized by a humid temperate climate through the growing season. Crop losses up to 30% have been reported to be caused by Phomopsis cane and leaf spot.
Glomerella graminicola is an economically important crop parasite affecting both wheat and maize where it causes the plant disease Anthracnose Leaf Blight.
Colletotrichum acutatum is a plant pathogen and endophyte. It is the organism that causes the most destructive fungal disease, anthracnose, of lupin species worldwide. It also causes the disease postbloom fruit drop on many varieties of citrus, especially Valencia and navel oranges in Florida.
Pseudocercosporella capsellae is a plant pathogen infecting crucifers. P. capsellae is the causal pathogen of white leaf spot disease, which is an economically significant disease in global agriculture. P. capsellae has a significant effect on crop yields on agricultural products, such as canola seed and rapeseed. Researchers are working hard to find effective methods of controlling this plant pathogen, using cultural control, genetic resistance, and chemical control practices. Due to its rapidly changing genome, P. capsellae is a rapidly emerging plant pathogen that is beginning to spread globally and affect farmers around the world.
Phytophthora citrophthora, also known as brown rot of citrus, is a soil borne oomycete that infects several economically important citrus crops. A diagnostic symptom of P. citrophthora is gummosis, wherein lesions around the base of the tree exude sap. Other common symptoms include dark longitudinal lesions forming at the soil line, a sour smell, and eventual cracking of the bark. Advanced symptoms include yellowing and necrosis of the tree canopy. Girdling action caused by the pathogen around the trunk can often cause the collapse of the tree. Resistant lemon varieties have been developed and their implementation has been effective at controlling the spread of the disease. Fruits that have been infected with P. citrophthora exhibit symptoms of brown rot characterized by a distinct odor. This disease is most active in the moderate temperatures of spring, fall, and winter months, opposite of most other Phytophthora species.
Alternaria japonica is a fungal plant pathogen. It is a cause of black spot disease in cruciferous plants. It is not a major source of crop loss, but is considered dangerous for plants during the seedling stage.
Mucor piriformis is a plant pathogen that causes a soft rot of several fruits known as Mucor rot. Infection of its host fruits, such as apples and pears, takes place post-harvest. The fungi can also infect citrus fruits.
Cadophora malorum is a saprophytic plant pathogen that causes side rot in apple and pear and can also cause disease on asparagus and kiwifruit. C. malorum has been found parasitizing shrimp and other fungal species in the extreme environments of the Mid-Atlantic Ridge, and can be categorized as a halophilic psychrotrophic fungus and a marine fungus.
Alternaria solani is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato. Despite the name "early", foliar symptoms usually occur on older leaves. If uncontrolled, early blight can cause significant yield reductions. Primary methods of controlling this disease include preventing long periods of wetness on leaf surfaces and applying fungicides. Early blight can also be caused by Alternaria tomatophila, which is more virulent on stems and leaves of tomato plants than Alternaria solani.
Didymella bryoniae, syn. Mycosphaerella melonis, is an ascomycete fungal plant pathogen that causes gummy stem blight on the family Cucurbitaceae, which includes cantaloupe, cucumber, muskmelon and watermelon plants. The anamorph/asexual stage for this fungus is called Phoma cucurbitacearum. When this pathogen infects the fruit of cucurbits it is called black rot.
Fusarium acuminatum is a fungal plant pathogen.
Diaporthe phaseolorum var. caulivora is a fungal plant pathogen which infects soybean, causing soybean stem canker.
Monilinia oxycocci (Woronin) Honey,, common names cranberry cottonball, cranberry hard rot, tip blight, is a fungal infection of large cranberry and small cranberry. The tips of young flowering shoots wilt before they flower. Fruit that forms on the plant can then be infected by the asexual spores traveling through the plant, causing the berries to harden, turn cottony on the inside, and dry out instead of maturing. The berries are filled with a cotton-like fungus and are generally yellowish with tan stripes or blotches at maturity, making them unmarketable. It results in important economic impacts on many cranberry marshes, particularly in Wisconsin.
Fusarium mangiferae is a fungal plant pathogen that infects mango trees. Its aerial mycelium is white and floccose. Conidiophores on aerial mycelium originating erect and prostrate from substrate; they are sympodially branched bearing mono and polyphialides. Polyphialides have 2–5 conidiogenous openings. Phialides on the aerial conidiophores mono- and polyphialidic. Sterile hyphae are absent. Microconidia are variable in shape, obovoid conidia are the most abundant type, oval to allantoid conidia occurring occasionally. Microconidia mostly 0-septate with 1-septate conidia occurring less abundantly. Sporodochia are present. Macroconidia are long and slender, usually 3–5 septate. Chlamydospores are absent.
Peach scab, also known as peach freckles, is a disease of stone fruits caused by the fungi Cladosporium carpophilum. The disease is most prevalent in wet and warm areas especially southern part of the U.S. as the fungi require rain and wind for dispersal. The fungus causes scabbing, lesions, and defoliating on twig, fruit, and leaf resulting in downgrade of peach quality or loss of fruits due to rotting in severe cases.
Stenocarpella maydis (Berk.) Sutton is a plant pathogenic fungus and causal organism of diplodia ear and stalk rot. Corn and canes are the only known hosts to date. No teleomorph of the fungus is known.
Bitter rot of apple is a fungal disease of apple fruit that is caused by several species in the Colletotrichum acutatum and Colletotrichum gloeosporioides species complexes. It is identified by sunken circular lesions with conical intrusions into the apple flesh that appear V-shaped when the apple is cut in half through the center of the lesion. It is one of the most devastating diseases of apple fruit in regions with warm wet weather.
Lambertella corni-maris is a small ascomycete fungi. It grows in deciduous fruit areas, and causes postharvest Lambertella rot on apple fruits. The species also forms a mycoparasitism relationship with Monilinia fructigena. It is the type species of the genus Lambertella.