Black pod disease

Last updated
Black pod disease
Common namesBlack pod disease of cocoa
Causal agents Phytophthora palmivora
Phytophthora megakarya
Hostscocoa ( Theobroma cacao )
EPPO Code PHYTPL

Black pod disease is a fungal disease of Cocoa trees. It is mostly found in tropical areas where cocao trees grow, and its spores are spread via the heavy rainfalls that can occur in tropical climates. Annually, the pathogen can cause a yield loss of up to 1/3, and up to 10% of total trees can be lost completely.

Contents

The pathogen can be found anywhere on the cocoa trees, but is most notable for the black mummified appearance it gives to the fruit of the cocoa tree. Preventing the spread of the pathogen prior to infection is the best means of control. The pathogen can be greatly reduced if leaf litter is allowed to stay on the ground, otherwise, chemical control can be used for more severe cases.

Disease cycle, symptoms and signs

The symptom of black pod disease is a necrotic lesion on the cocoa pod that is brown or black in color, which eventually enlarges to cover the whole pod. White mycelia growth on lesions that appear several days after infection is a sign of the causal pathogen of black pod disease, which is Phytophthora spp.

Black pod disease starts when the infected pod shows some little yellow spots, which eventually turn brown and enlarge to a dark brown or black lesion within five days. The lesion is fast growing and covers the entire pod after eight days of infection. The infection does not only occur on the pod surface, but also invades inside the pod affecting the beans. The growth of white mycelia on the black pod is visible after 11 days and the sporulation is initiated. The dispersal of sporangia or zoospores through water, ants and other insects occurs at this stage and will infect other healthy pods nearby. Direct contact of a black pod with healthy pods also leads to the spread of disease. [1] In addition, the infected flower cushion and mummified pods are the locations for P. palmivora survival during the dry season, where the pathogen will grow and continue to infect other developing pods [2] The infection occurs at any stage of pod development, where it causes wilting and dying of young pods and destroyed the beans of mature pods. [3] [4] The fully infected pods (the mummified pod), which then become dehydrated, are capable of providing the inoculum of P. palmivora for at least 3 years. [5] P. megakarya causes the same symptom as P. palmivora, but the occurrence is faster and generally produces greater amount of spores. Both P. palmivora and P. megakarya also caused canker on bark, flower cushion and chupóns, and cankers on the base could extend to the main roots. Cankers were identified as one of the inoculum sources for black pod disease. [6] Furthermore, the pattern of infection caused by P. megakarya starts from the ground and moves up to the canopy, however there is no distinct pattern of disease infection caused by P. palmivora was reported. [7] This pattern of infection could be due to P. megakarya and P. palmivora that were found to survive in soil [8] and P. megakarya could be surviving in the roots of a few species of shade trees found in cocoa plantations. [9]

Hosts

Black pod disease, while its name indicates that it is found in Theobroma cacao , also has different hosts. For example, P. megakarya has been detected in the roots of shade trees of Western Africa. [3] While these trees can also be affected by the pathogen it is because of the market value of the cocoa trees that all emphasis and research on the disease is done on cocoa trees.

Cocoa trees

In the cocoa trees, P. megakarya infects the bark, flowers, and trees with cankers. These cankers will often exude a reddish gum reducing the life of the tree, in turn, reducing the yield of the plant. The most devastating place the pathogen attacks is in the flowers, as these flowers are where the cocoa fruit will set. An infected flower will produce infected fruit, which will turn black and be unsuitable for processing.

Pathogen

Seven different pathogens have been named to cause black pod disease across world. All of the pathogens are found in the genus Phytophthora (a plant-damaging Oomycetes). The seven species responsible for black pod disease are; P. capsici, P. citrophthora, P. megasperma, P. katsurae, P. palmivora, and P. megakarya. While all of these pathogens can cause black pod disease, the two major pathogens responsible for black pod are P. palmivora and P. megakarya. [3] P. capsici and P. citrophthora are found in Central and South America, while others such as P. megakarya is found in Central and Western Africa.

Environment

P. megakarya is found in Central and Western Africa. [3] During the cooler wetter times of the year, there is a spike in the incidents of black pod disease as when compared to the hotter more dry times of the year. [10] The disease has a spike in growth shortly after a rainfall. The humid weather that is associated with this pathogen and all other black pod disease pathogens is needed as the sporangia forms and starts distributing spores through rainfall, splashing water, and running water. [11]

Inoculum dispersal

Soil and litter

The spread of infection to pods above bare soil was shown to be greater relative to pods above litter. [12] The reason for this is due to the splash of rain from bare soil spreads the inoculum to pods. However, litter under the tree prevented water droplets from splashing the soil particles as well as the inoculum beneath the litter to the above pods. Furthermore, it was also reported that pods near the ground showed greater infections compared to higher pods due to greater soil was splashed and stick on the lower pods, therefore causes more infections.

Air and water dispersal from sporulating pods

The spread of spores through air from infected pods was observed, and some assumptions regarding this mechanism of dispersion has been made in previous studies, [13] however it has remained uncertain due to unreliable results from an experiment that collected some spores in the air using the volumetric spore trap, where a small amount of spores were found in the trap - most likely due to realative humidity capturing the spores in micrometer sized droplets suspended in the air. Conversely, the dispersal of inoculum via rain is considered an effective mechanism in spreading the inoculum. It was assumed that under close canopy, less water will reach the sporulating pods to spread the inoculum, however, rain drops from leaves and branches could also splash the inoculum to the surroundings. Infected pods lying on the ground or litter could also spread the inoculum, yet greater infection was observed on pods located under infected pods hanging on the tree compared to pods at the same level of infected pods. It was reported that splash of wind-blown droplets from the infected pods are also able to infect pods on different trees nearby [12]

Invertebrate

The dispersal of the disease is also associated with the invertebrate vectors. Tent building ants such as Crematogaster striatula and Camponotus acvapimensis were reported as the primary vector in disseminating the spores of P. palmivora from infected pods to healthy pods in Ghana. [14] C. striatula was thought to be the most important vector that is responsible for black pod losses due to its building tent behavior as well as its dominancy within the area under particular condition. In Ghana, C. striatula removes the outer layer of cocoa pod and uses this material to construct the tent. Therefore, this ant effectively spread the disease by transporting the spores from the infected pods on the ground or on trees to healthy pods. Several other ant species namely C. africana, C. clariventris and C. depressa were also responsible for the spread of the disease besides C. striatula [14] In addition, Camponotus acvapimensis, another type of tent-building ant that uses soil as building materials for tent construction was identified as the most important agent to spread the inoculum in Nigeria. [15] Soil was identified as the source of inoculum for P. megakarya [12] and therefore, it was implied that this ant species might use the infected soil to build tents, which infects healthy pods on trees.

Other invertebrates that were reported to be associated with spreading the disease are several species of beetle, snail, caterpillar and millipedes. [13] Fecal samples from these organisms were found to contain viable spores of P. palmivora. It was reported that beetle of family Nitidulidae is the most common vector for black pod as it was found 50 to 60% of black pod occurrences. These invertebrates consume the outer layer of the infected pods and incidentally ingest the mycelium and spores of the pathogen, thus spread the pathogen to other healthy pods.

Disease management

There are several methods available in order to control black pod disease such as cultural, chemical and biological control. In addition, the cultivation of varieties that resistant to black pod is an alternative in order to reduce disease incidence.

Cultural control

Several cultural practices to manage black pod disease could be implemented in cocoa plantation. [4] A spacing of 3.1 x 3.1m and pruning of trees are recommended for cocoa planting in order to allow more light and air flow around the trees. This will reduce the level of humidity that is causing black pod disease. The removal of pods with black pod symptom should also be done in favor to eliminate the source of inoculum. In another study, the utilization of litter mulch under cocoa plantation has been reported in Papua New Guinea, which has some negative effect on the population of P. palmivora, and therefore could reduce the pod infection especially at the beginning of raining season. Leaf litter showed rapid decline in pathogen recovery of colonized cocoa tissue after 18 weeks, relative to grass ground cover. [16] An explanation for this is due to higher moisture content and microbial activity of other microbes under leaf litter that reduces the survival of Phytophthora cinnamomi as documented by Aryantha et al. (2000). [17] More frequent ripe pod harvest (i.e. twice a week) and removal of infected pod on the ground was demonstrated to significantly reduced disease occurrence and improve pod yield compared to less frequent harvest and removal (i.e. once a month). In addition, scattered healthy pod on the ground should also be removed, as it will be infected and become the source of inoculum later. [18] Sanitation is one cultural method to control for black pod disease. Sanitation practices include weed removal, pruning, thinning and removal of infected and mummified pods every two weeks [7] in order to eliminate the source for inoculum. Phytosanitary pod removal was observed to significantly reduce disease occurrences by 9–11% to 22–31%, where this practice removes the source for secondary inoculum. However, increase in disease incidence after raining season was observed to be most likely due to the spread of inoculum from survival site by the rain. The application of fungicide following sanitation is commonly performed for an effective control of disease, as sanitation practice alone would not eliminate the source of inoculum and still causes greater black pod incident compared to sanitation followed by at least one fungicide application [7]

Chemical control

The application of copper fungicide has been shown to significantly reduce the number of black pod incidents in Nigeria. Metalaxyl (Ridomil) and cuprous oxide (Perenox) were identified to be successful in increasing the number of harvested healthy pod compared to the application of fosetyl aluminium (Aliete) and control treatment. On top of that, the timing of fungicide application has some positive effect on the final pod yield where this plot produced greater yield than the unsprayed plot. The application was done before August, which is before the main disease epidemic that usually occurs in September and October. [8] The recommended standard for fungicide application to control black pod disease caused by P. megakarya for a season is 6 to 8 times of application in every 3–4 weeks. However, the adoption of recommended application was very low among farmers in Ghana. Therefore, an experiment with a reduced number of fungicide applications demonstrated that there was 25 to 45% reduction in disease incidence. [7] In terms of disease control and yields, sanitation and three applications of Ridomil 72 plus (12% metalaxyl + 60% copper-1-oxide) fungicide showed a better control compared to sanitation alone and sanitation with one or two fungicide applications. However, reduced in fungicide application was shown to be significantly less effective than the recommended standard fungicide application. It was suggested that the understanding regarding the source of inoculum, the amount of infective inoculum production and how the disease is disseminated is important in order to identify the appropriate and economical method in fungicide application as well as for an effective control of the disease. For example, the application of fungicide on the trunk will help farmers to control the spread of the disease up in the canopy, as it is difficult to reach the canopy during fungicide application. This will eventually save more time, labor and cost for disease management. [7]

Cultural and chemical control

In Ghana, a study that combined the sanitation and fungicide application showed a significant reduction in the percentage of disease incidence, where greater black pod incident were observed from pods on the trunk than the canopy in control treatment (no fungicide application). This suggested that the application of fungicide on the trunk would protect pods from infection, therefore reduce primary and secondary infection rate, both on the trunk and in the canopy. In addition, the application of systemic (potassium phosphonate) with one and double injection (20 ml and 40 ml of fungicide for each injection frequency), and semi-systemic (metalaxyl) fungicide showed better control compared to contact fungicides (copper based fungicide) in both locations that were used in the experiment. [7]

Biological control

Chris Tonaldo applying chemical fungicide on cocoa ChrisTonaldo spreading coacoa.jpg
Chris Tonaldo applying chemical fungicide on cocoa

Heavy application of chemical fungicide eventually leads to resistance in pathogens and causes soil and water pollution. Hence, more sustainable and environmental friendly method should be established and implemented, such as biological control. Several species of fungi from the genera of Trichoderma were identified to be beneficial endophytes to control black pod caused by Phytophthora spp. An isolate of Trichoderma asperellum from soil was observed as a potential mycoparasite for P. megakarya where this fungus has the potential to reduce black pod incidence under field conditions in Cameroon. It was reported that moderate black pod cases (47%) occurred in the T. asperellum treatment compared to untreated trees (71%) and chemical fungicide (1.73%). [19] Another species, T. virens, also has been documented to reduce black pod incidence in Peru. [20] In Brazil, a new species known as Trichoderma martiale Samuels, sp. nov. was identified as an endophyte on cocoa, which has the ability to reduce black pod symptoms caused by P. megakarya. [21] This endophyte species survives on cocoa pods, and has the ability to establish a long endophytic association with the host (about 3.5 months). Nevertheless, the protection against black pod via biological control is not as effective as the control using chemical fungicides. [19] [21]

Resistant variety

There is no specific variety of cocoa that shows resistance to Phytophthora infection, and the establishment and utilization of resistant varieties most likely depends on the region. Numerous breeding programs have been established worldwide in order to screen and test local hybrids for resistance to Phytophthora spp. For example, a study in Cameroon assessed the performance of local cocoa cultivars (the southern and northern Cameroon cultivar) compared to the local and international gene bank cultivars. The local genebank cultivar consisted of F1 hybrid of Upper Amazon X Trinidad, and an international cultivar from Papua New Guinea and Latin America were provided through International Cocoa Genebank, Trinidad. Based on the information provided by farmers and leaf disc tests to assess resistance, the local cultivars selected from farmers field showed greater resistance to P. megakarya compared to others. Thus, it was concluded that there are some potentially resistant varieties available in this area. [22] In addition, further work towards developing black pod-resistant varieties is being done by CEPLAC (Executive Plan of Cocoa Farming) agency in Brazil [23] and hopefully more breeding program focusing on black pod resistant will be established to produce commercialized resistant varieties.

Importance

The United States chocolate industry consumes 1.4 billion dollars of cocoa and supplies 68,450 jobs throughout the United States. [24] With this industry being so important not only in the US but also all over the world, the elimination of black pod disease is of high importance.

Related Research Articles

<span class="mw-page-title-main">Fusarium wilt</span> Fungal plant disease

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.

<span class="mw-page-title-main">Apple scab</span> Plant disease caused by fungus

Apple scab is a common disease of plants in the rose family (Rosaceae) that is caused by the ascomycete fungus Venturia inaequalis. While this disease affects several plant genera, including Sorbus, Cotoneaster, and Pyrus, it is most commonly associated with the infection of Malus trees, including species of flowering crabapple, as well as cultivated apple. The first symptoms of this disease are found in the foliage, blossoms, and developing fruits of affected trees, which develop dark, irregularly-shaped lesions upon infection. Although apple scab rarely kills its host, infection typically leads to fruit deformation and premature leaf and fruit drop, which enhance the susceptibility of the host plant to abiotic stress and secondary infection. The reduction of fruit quality and yield may result in crop losses of up to 70%, posing a significant threat to the profitability of apple producers. To reduce scab-related yield losses, growers often combine preventive practices, including sanitation and resistance breeding, with reactive measures, such as targeted fungicide or biocontrol treatments, to prevent the incidence and spread of apple scab in their crops.

<span class="mw-page-title-main">Black rot (grape disease)</span> Species of fungus

Grape black rot is a fungal disease caused by an ascomycetous fungus, Guignardia bidwellii, that attacks grape vines during hot and humid weather. “Grape black rot originated in eastern North America, but now occurs in portions of Europe, South America, and Asia. It can cause complete crop loss in warm, humid climates, but is virtually unknown in regions with arid summers.” The name comes from the black fringe that borders growing brown patches on the leaves. The disease also attacks other parts of the plant, “all green parts of the vine: the shoots, leaf and fruit stems, tendrils, and fruit. The most damaging effect is to the fruit”.

<i>Phytophthora palmivora</i> Species of single-celled organism

Phytophthora palmivora is an oomycete that causes bud-rot of palms, fruit-rot or kole-roga of coconut and areca nut. These are among the most serious diseases caused by fungi and moulds in South India. It occurs almost every year in Malnad, Mysore, North & South Kanara, Malabar and other areas. Similar diseases of palms are also known to occur in Sri Lanka, Mauritius, and Sumatra. The causative organism was first identified as P. palmivora by Edwin John Butler in 1917.

<i>Phytophthora cactorum</i> Species of single-celled organism

Phytophthora cactorum is a fungal-like plant pathogen belonging to the Oomycota phylum. It is the causal agent of root rot on rhododendron and many other species, as well as leather rot of strawberries.

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.

Phytophthora nicotianae or black shank is an oomycete belonging to the order Peronosporales and family Peronosporaceae.

<i>Phytophthora erythroseptica</i> Species of single-celled organism

Phytophthora erythroseptica—also known as pink rot along with several other species of Phytophthora—is a plant pathogen. It infects potatoes causing their tubers to turn pink and damages leaves. It also infects tulips (Tulipa) damaging their leaves and shoots.

<i>Ascochyta</i> Genus of fungi

Ascochyta is a genus of ascomycete fungi, containing several species that are pathogenic to plants, particularly cereal crops. The taxonomy of this genus is still incomplete. The genus was first described in 1830 by Marie-Anne Libert, who regarded the spores as minute asci and the cell contents as spherical spores. Numerous revisions to the members of the genus and its description were made for the next several years. Species that are plant pathogenic on cereals include, A. hordei, A. graminea, A. sorghi, A. tritici. Symptoms are usually elliptical spots that are initially chlorotic and later become a necrotic brown. Management includes fungicide applications and sanitation of diseased plant tissue debris.

<i>Alternaria solani</i> Species of 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.

Phytophthora megakarya is an oomycete plant pathogen that causes black pod disease in cocoa trees in west and central Africa. This pathogen can cause detrimental loss of yield in the economically important cocoa industry, worth approximately $70 billion annually. It can damage any part of the tree, causing total yield losses which can easily reach 20-25%. A mixture of chemical and cultural controls, as well as choosing resistant plant varieties, are often necessary to control this pathogen.

<i>Moniliophthora perniciosa</i> Species of fungus

Moniliophthora perniciosa is a fungus that causes "witches' broom disease" (WBD) of the cocoa tree T. cacao. This pathogen is currently limited to South America, Panama and the Caribbean, and is perhaps one of the best-known cocoa diseases, thought to have co-evolved with cocoa in its centre of origin.

Elsinoë mangiferae, common name "mango scab", is also known Denticularia mangiferae or Sphaceloma mangiferae (anamorph). It is an ascomycete plant pathogen native to tropical regions and specific for survival on only one host, the mango. Originally described in 1943 from Florida and Cuba specimens, this pathogen has since spread worldwide and is becoming a pathogen of great concern for the mango industries in Australia and India. The species was first described formally in 1946.

Rosellinia bunodes is a plant pathogen infecting several hosts including avocados, bananas, cacao and tea.

<i>Phytophthora kernoviae</i> Species of oomycete

Phytophthora kernoviae is a plant pathogen that mainly infects European beech and Rhododendron ponticum. It was first identified in 2003 in Cornwall, UK when scientists were surveying for the presence of Phytophthora ramorum. This made it the third new Phytophthora species to be found in the UK in a decade. It was named Phytophthora kernoviae after the ancient name for Cornwall, Kernow. It causes large stem lesions on beech and necrosis of stems and leaves of Rhododendron ponticum. It is self-fertile. It has also been isolated from Quercus robur and Liriodendron tulipifera. The original paper describing the species, stated it can infect Magnolia and Camellia species, Pieris formosa, Gevuina avellana, Michelia doltsopa and Quercus ilex. Since then many other plants have been identified as natural hosts of the pathogen. Molecular analysis has revealed that an infection on Pinus radiata, recorded in New Zealand in 1950, was caused by P. kernoviae. The pathogen was also noted on Drimys winteri, Gevuina avellana, Ilex aquifolium, Quercus ilex, Vaccinium myrtillus, Hedera helix, Podocarpus salignas.

This article summarizes different crops, what common fungal problems they have, and how fungicide should be used in order to mitigate damage and crop loss. This page also covers how specific fungal infections affect crops present in the United States.

<span class="mw-page-title-main">Ascochyta diseases of pea</span> Group of diseases affecting pea plants

Ascochyta blights occur throughout the world and can be of significant economic importance. Three fungi contribute to the ascochyta blight disease complex of pea. Ascochyta pinodes causes Mycosphaerella blight. Ascochyta pinodella causes Ascochyta foot rot, and Ascochyta pisi causes Ascochyta blight and pod spot. Of the three fungi, Ascochyta pinodes is of the most importance. These diseases are conducive under wet and humid conditions and can cause a yield loss of up to fifty percent if left uncontrolled. The best method to control ascochyta blights of pea is to reduce the amount of primary inoculum through sanitation, crop-rotation, and altering the sowing date. Other methods—chemical control, biological control, and development of resistant varieties—may also be used to effectively control ascochyta diseases.

<span class="mw-page-title-main">Cherry leaf spot</span> Plant fungal disease

Cherry leaf spot is a fungal disease which infects cherries and plums. Sweet, sour, and ornamental cherries are susceptible to the disease, being most prevalent in sour cherries. The variety of sour cherries that is the most susceptible are the English morello cherries. This is considered a serious disease in the Midwest, New England states, and Canada. It has also been estimated to infect 80 percent of orchards in the Eastern states. It must be controlled yearly to avoid a significant loss of the crop. If not controlled properly, the disease can dramatically reduce yields by nearly 100 percent. The disease is also known as yellow leaf or shothole disease to cherry growers due to the characteristic yellowing leaves and shot holes present in the leaves upon severe infection.

<span class="mw-page-title-main">Banana freckle</span> Fungal disease of bananas

Banana freckle is a disease caused by the fungus Guignardia musae (teleomorph) or Phyllosticta musarum (anamorph). Generally, the causal agent of disease is referred to as Guignardia-Phyllosticta sp. There are several different strains of the fungus that exist to infect different banana varieties around the globe. Symptoms include yellowing of the tissue and formation of small dark brown spots on the leaves and fruit. Within the spots, conidia or pycnidia can be found. Banana freckle is easily propagated and spread from plant to plant by rain splash and movement of infected tissue or fruit. Management of the disease consists of cutting out infected leaves, using the paper bag method, fungicide application, and proper sanitation techniques it can be stopped by applying vegeta to it. This devastating disease is extremely relevant for the major banana exporting countries of the world. In the absence of chemical control, there is about a 78% yield loss. Banana freckle disease needs to be carefully monitored in order to prevent further spread of the disease.

Alternaria black spot of canola or grey leaf spot is an ascomycete fungal disease caused by a group of pathogens including: Alternaria brassicae, A. alternata and A. raphani. This pathogen is characterized by dark, sunken lesions of various size on all parts of the plant, including the leaves, stem, and pods. Its primary economic host is canola. In its early stages it only affects the plants slightly by reducing photosynthesis, however as the plant matures it can cause damage to the seeds and more, reducing oil yield as well.

References

  1. ↑ Philip-Mora, Wilbert; Rolando Cerda (2009). "Catalog: Cacao Diseases in Central America" (PDF). Tropical Agricultural Research and Higher Education Center, CATIE. Archived from the original (PDF) on 2013-12-12. Retrieved 20 November 2013.
  2. ↑ Brasier, C. M.; M.J. Griffin; A.C. Maddison (1981). "Cocoa black pod Phytophthoras". In P.H. Gregory and A.C. Maddison) (ed.). Epidemiology of Phytophthora on cocoa in Nigeria. UK: Commonwealth Mycological Institute, Kew. pp. 18–30.
  3. 1 2 3 4 Guest, D. (2007). "Black Pod: Diverse pathogens with a global impact on cocoa yield". Phytopathology. 97 (12): 1650–1653. doi:10.1094/phyto-97-12-1650. PMID   18943728.
  4. 1 2 Luseni, M.M.; S. Kroma (2012). "Black pod disease of cacao" (PDF). www.plantwise.org. doi:10.1079/pwkb.20127801283. S2CID   254006087.{{cite journal}}: Cite journal requires |journal= (help)
  5. ↑ Dennis, J.J.C.; J.K. Konam (1994). "Phytophthora palmivora cultural control methods and their relationship to disease epidemiology on cocoa in Papua New Guinea". 11th International Cocoa Research Conference. Cocoa Producers Alliance. 11: 953–957.
  6. ↑ Gregory, P.H; A.C. Maddison (1981). Epidemiology of Phytophthora on Cocoa in Nigeria. UK: Commonwealth Mycological Institute, Kew.
  7. 1 2 3 4 5 6 Opoku, I.Y.; A.Y. Akrofi; A.A. Appiah (2007). "Assessment of sanitation and fungicide application directed at cocoa tree trunks for the control of Phytophthora black pod infections in pods growing in the canopy". Eur. J. Plant Pathol. 117 (2): 167–175. doi:10.1007/s10658-006-9082-8. S2CID   6620069.
  8. 1 2 Ward, M.R.; A.C. Maddison; A.A. Adebayo (1981). "The epidemic on sprayed cocoa at Gambari". In P. H. Gregory and A. C. Maddison (ed.). Epidemiology of Phytophthora on Cocoa in Nigeria. UK: Commonwealth Mycological Institute, Kew. pp. 145–162.
  9. ↑ Opoku, I.Y.; A.Y. Akrofi; A.A. Appiah (2002). "Shade trees are alternative hosts of the cocoa pathogen Phytophthora megakarya". Crop Prot. 21 (8): 629–634. doi:10.1016/s0261-2194(02)00013-3.
  10. ↑ Dakwa, J.T (1973). "The relationship between black pod incidence and the weather in Ghana". Ghana J. Agric. Sci. 6: 93–102.
  11. ↑ Bowers, J.H.; B.A. Bailey; P.K. Hebbar; S. Sanogo; R.D. Lumsden (2001). "The impact of plant diseases on world chocolate production". Plant Health Progress. Archived from the original on 2013-12-12. Retrieved 2013-11-22.
  12. 1 2 3 Maddison, A.C.; M.J. Griffin (1981). "Detection and movement of inoculum". In P.H. Gregory and A.C. Maddison (ed.). Epidemiology of Phytophthora on Cocoa in Nigeria, Phytopathological. UK: Commonwealth Mycological Institute, Kew. pp. 31–49.
  13. 1 2 Thorold, C.A. (1952). "Airborne dispersal of Phytophthora palmivora, causing black pod disease in Theobroma cacao". Nature. 170 (4330): 718–719. Bibcode:1952Natur.170..718T. doi:10.1038/170718a0. PMID   13002424. S2CID   4264153.
  14. 1 2 Evans, H.C. (1971). "Transmission of Phytophthora pod rot of cocoa by invertebrates". Nature. 232 (5309): 346–347. Bibcode:1971Natur.232..346E. doi:10.1038/232346a0. PMID   5094846. S2CID   4181889.
  15. ↑ Taylor, B.; M.J. Griffin (1981). "The role and relative importance of different ant species in the dissemination of black pod disease of cocoa". In P.H. Gregory and A.C. Maddison (ed.). Epidemiology of Phytophthora on Cocoa in Nigeria. UK: Commonwealth Mycological Institute, Kew. pp. 114–131.
  16. ↑ Konam, J.K.; D.I. Guest (2002). "Leaf litter mulch reduces the survival of Phytophthora palmivora under cocoa trees in Papua New Guinea". Australas. Plant Pathol. 31 (4): 381–383. doi:10.1071/ap02043. S2CID   40787476.
  17. ↑ Aryantha, I.P.; R. Cross; D.I. Guest (2000). "Suppression of Phytophthora cinnamomi in potting mixes amended with uncomposted and composted animal manures". Phytopathology. 90 (7): 775–782. doi:10.1094/PHYTO.2000.90.7.775. PMID   18944498.
  18. ↑ Dennis, J.J.C.; J.K. Konam (1994). "Phytophthora palmivora cultural control methods and their relationship to disease epidemiology on cocoa in Papua New Guinea". 11th International Cocoa Research Conference. Cocoa Producers Alliance. 11 (953–957).
  19. 1 2 Deberdt, P.; C.V. Mfegue; P.R. Tondje; M.C. Bon; M. Ducamp; C. Hurard; B.A.D. Begoude; M. Ndoumbe-Nkeng; P.K. Hebbar; C. Cilas (2008). "Impact of environmental factors, chemical fungicide and biological control on cacao pod production dynamics and black pod disease (Phytophthora megakarya) in Cameroon". Biological Control. 44 (2): 149–159. doi:10.1016/j.biocontrol.2007.10.026.
  20. ↑ Krauss, U.; W. Soberanis (2002). "Effect of fertilization and biocontrol application frequency on cocoa pod diseases". Biological Control. 24: 82–89. doi:10.1016/s1049-9644(02)00007-5.
  21. 1 2 Hanada, R.E; T.J. Souza; A.W.V. Pomella; K. P. Hebbar; J. O. Pereira; A. Ismaiel; G.J. Samuels (2008). "Trichoderma martiale sp. nov., a new endophyte from sapwood of Theobroma cacao with a potential for biological control". Mycol. Res. 112 (11): 1335–1343. doi:10.1016/j.mycres.2008.06.022. PMID   18672059. Archived from the original on 2020-11-29. Retrieved 2018-12-29.
  22. ↑ Efombagn, M.I.B.; S. Nyassé; O. Sounigo; M. Kolesnikova-Allen; A.B. Eskes (2007). "Participatory cocoa (Theobroma cacao) selection in Cameroon: Phytophthora pod rot resistant accessions identified in farmers' fields". Crop Prot. 26 (10): 1467–1473. doi:10.1016/j.cropro.2006.12.008.
  23. ↑ ICCO - International Cocoa Organization. (2013). "Pest and Diseases". Archived from the original on 2014-02-14. Retrieved 2013-11-21.
  24. ↑ U.S. Bureau of Census (2010). "Current Industrial Reports: MA311D - Confectionery".
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.