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Integrated Pest Management

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Click here to download the corresponding chapter from the Technical Manual

Chapter 16: Integrated Pest Management

Les pestes sont une préoccupation constante pour tous les fermiers. Comme chaque fermier sait, elles peuvent facilement détruire des récoltes entières en peu de temps. Par contre, les pestes ont tendance de préférer des récoltes particulières. Un des nombreux avantages importants des jardins forêt est que leur diversité naturelle veut dire qu’une seule peste affectera seulement une des nombreuses récoltes qui produisent à n’importe quel moment. Donc même si vous avez une infestation de peste, vous aurez toujours des autres récoltes qui fourniront de la nourriture et des opportunités de revenu.

Ceci dit, c’est dans votre meilleur intérêt de contrôler n’importe quelles pestes autant que possible. Les pratiques agricoles modernes et intensives dépendent souvent sur des pesticides chères et synthétiques pour tuer les pestes, amenant souvent des effets négatifs à l’environnement, sans parler des risques de santé pour ceux qui les gèrent ces produits chimiques toxiques incorrectement. De plus, les pesticides tuent généralement tous les insectes, inclus les insectes bénéfiques que protègent vos récoltes naturellement, et tous les organismes bénéfiques qui vivent dans et autour de vos terres – qui sont tellement indispensables pour maintenir la fertilité de votre terre.

Avec l’approche de jardin forêt, nous encourageons des mesures naturelles et organiques pour contrôler les pestes, en utilisant une approche appelée la gestion intégrée de peste. Cette gestion est une approche qui cherche à gérer les populations de peste au lieu de les contrôler ou les éradiquer. Elle demande une grande connaissance de peste, de récolte et d’environnement. Par conséquence, sa stratégie se concentre sur comment saisir les forces intrinsèques dans l’écosystème et diriger les populations de peste vers des limites acceptables au lieu de complètement les éliminer. Cette approche se concentre sur la gestion de peste au lieu de la gestion des pesticides. Cette stratégie évite les impacts environnementaux à terme long et court et aidera à assurer une productivité durable dans votre jardin forêt. La gestion intégrée de peste est un programme de gestion de peste exhaustif à long terme, basé sur les connaissances d’un écosystème qui considère les conséquences économiques, environnementales, et sociales des interventions. Cette approche demande une compréhension complexe des récoltes que vous cultivez, des terres dans lesquelles vous les cultivez, des pestes dans votre zone et leurs ennemies naturelles, et des interactions parmi eux-mêmes. Donc, c’est impossible de décrire ou de définir les approches de gestion intégrée de peste qui sont convenables pour chaque jardin forêt. Par contre, nous décrirons la philosophie générale, le procès pour développer une approche de gestion intégrée dans votre jardin forêt, une vue d’ensemble de base des nombreuses pestes communes que les fermiers affronteront probablement, et des conseils pour savoir quelles approches utiliser pour les gérer.. L’usage des pesticides et des autres approches qui traitent les symptômes au lieu des causes fondamentales ne sont pas durables et devraient être la dernière option au lieu de la première ligne de défense. Une stratégie de gestion intégrée de peste devraient toujours commencer avec la question: ‘Pourquoi est-ce-que la peste est une peste?’. La stratégie devrait aussi chercher comment adresser les faiblesses sous-jacentes dans les écosystèmes et/ou dans les pratiques agronomiques qui ont permises ces organismes d’atteindre un statut de peste. Un procès intégré L’intégration ou la compatibilité parmi les tactiques de gestion de peste est essentielle pour la gestion intégrée de peste. Simplement mélanger des tactiques de gestion différentes ne constitue pas une gestion intégrée de peste. Mélanger des tactiques de façon arbitraire peut en fait aggraver les problèmes de peste ou produire des autres effets involontaires. La gestion intégrée de peste reconnait qu’il n’y a pas une panacée pour le contrôle des pestes, puisque les pestes sont trop diverses pour être contrôlées avec seulement une mesure. La dépendance sur une seule tactique favorisera les pestes qui sont résistantes à cette pratique. Dans la gestion intégrée de peste, le contrôle intégré cherche à identifier le meilleur mélange de contrôles de peste pour un insecte en particulier. La détermination correcte de la cause du problème de peste (comprendre la biologie de peste) et l’écologie sont essentielles pour manipuler l’environnement à l’avantage de la récolte et au détriment de la peste.. Niveaux de peste acceptables La gestion intégrée de peste reconnaît que l’éradication d’une peste est rarement nécessaire ou même désirable, et n’est généralement pas possible. L’objectif principal de la gestion de peste n’est pas d’éliminer un organisme peste, mais de contrôler toutes les pestes à un niveau acceptable qui aura peu d’impact sur la productivité générale du système de jardin forêt. L’importance est le contrôle, pas l’éradication. La gestion intégrée de peste maintient qu’éliminer une population de peste entière est souvent impossible, et que la tentative peut être couteuse et écologiquement dangereuse et non-durable. La tâche initiale d’un programme de gestion intégrée de peste est d’établir des niveaux de pestes acceptables, ou des limites, et d’appliquer des contrôles quand ces limites sont dépassées. Ces limites dépendent du chantier et de la peste, c’est à dire que l’impact de certaines broussailles ou pestes dans un chantier peut être négligeable, mais considérable dans un autre chantier. En permettant la population de peste de survivre à une limite raisonnable, la pression de sélection est réduite. Ceci empêche les pestes de développer une résistance aux produits chimiques produits par les planes ou appliqués aux récoltes. Si beaucoup des pestes sont tuées, celles qui ont une résistance au produit chimique formeront une base génétique pour l’avenir qui sera encore plus résistante. En ne pas tuant les pestes, il y aura des pestes qui restent qui ne seront pas résistantes au produit chimique qui dilueront probablement les gènes résistants qui apparaissent.

Procès de gestion intégrée de peste

La gestion intégrée de peste est applicable pour tous les genres de jardins forêt et les compositions de variétés, et dans tous les climats et les conditions agro-écologiques. Il y a certaines mesures de base de gestion intégrée, inclus la rotation des récoltes, la gestion de la fertilité de la terre et la protection, qui peuvent beaucoup aider pour empêcher les pestes de se peupler dans votre jardin forêt. Par contre, ces approches ne contrôleront pas toutes les pestes. C’est extrêmement important que vous surveilliez les plantes dans votre jardin forêt prudemment et régulièrement. C’est aussi important que vous identifiez n’importe quels problèmes de pestes aussi tôt que possible, et que vous déterminez la meilleure approche pour les contrôler. Ce procès comprend:

L’identification correcte des dommages de peste et les pestes responsables

L’identification correcte de peste doit être le premier objectif. Vous devez connaître la peste avant que vous puissiez déterminer la meilleure approche pour la contrôler. Les cas d’erreurs d’identification peuvent causer des actions inefficaces. Si le dommage d’une plante est à cause de sur-arrosage, par instance, le problème peut être confondu avec une infection fongique, puisque de nombreuses infections virales et fongiques se développent avec des conditions humides. Ceci peut demander des méthodes de contrôle laborieuses et couteuses qui n’auraient pas d’effet sur la santé des plantes que vous essayez de protéger.

Biologie des cycles de vie de peste et d’hôte

Comprendre la croissance et le développement de récolte est un principe sous-jacent de la gestion intégrée de peste. Les interactions entre les pestes et les récoltes (et l’environnement) sont très importantes. C’est important de prudemment surveiller votre jardin forêt régulièrement pour identifier et réagir aux pestes avant qu’elles deviennent un problème sérieux. Dans certains cas, par contre, une fois que vous voyez une peste ça peut être trop tard pour faire quelque chose sauf utiliser des pesticides et accepter le prix et l’impact sur la santé de votre jardin forêt. Souvent, par contre, il y a une autre étape dans le cycle de vie qui est susceptible aux actions préventives. Par exemple, les broussailles qui se reproduisent avec les graines de l’année dernière peuvent souvent être évitées avec des paillis. Dans des autres cas, savoir ce dont la peste a besoin pour survivre – se nourrir avec un certain genre de plante, par exemple – peut vous permettre d’enlever cet élément de votre jardin forêt.

Évaluez et enregistrez les résultats

L’évaluation est souvent une des étapes les plus importantes dans la gestion intégrée de peste. C’est le procès de revoir une approche de gestion intégrée de peste et les résultats qu’elle génère. Poser les questions suivantes est utile: Est-ce-que les mesures que vous avez pris contrôlent la population efficacement? Est-ce-que cette méthode était assez prudente? Y avait-il des effets imprévus? Quelle est la prochaine étape? Comprendre l’efficacité de l’approche de gestion intégrée de peste vous permet de faire des modifications au plan de gestion avant que les pestes atteignent la limite et demande de l’action de nouveau.

Tactiques de gestion de peste

Il y a des différentes tactiques de gestion de peste pour les éradiquer. Ces tactiques comprennent la résistance de l’hôte, des contrôles biologiques, mécaniques, sanitaires, culturels, et quand rien d’autre ne marche, chimiques. La tactique de gestion fondamentale implique la maximisation des éléments incorporés de réduction de peste d’un écosystème. Les mécanismes moléculaires ou génétiques sont potentiellement manifestés par le nombre de ces tactiques plus précises. Chaque catégorie, discutée ci- dessous, emploie des mécanismes différents pour éradiquer les populations.

Contrôle biologique

Ceci implique l’usage d’autres êtres vivants qui sont l’ennemie des pestes pour les contrôler. La plantation de plantes insectariums et nectaires et des confondeurs de pestes aromatiques, par instance, peuvent repousser les pestes ou attirer leurs prédateurs naturels. La gestion intégrée de peste est principalement visée aux systèmes développant basé sur les méthodes biologiques et non-chimiques autant que possible.

Résistance de la plante hôte

Ceci implique l’usage des variétés de plantes qui ont des caractéristiques économiques désirables, mais sont moins attirantes pour les pestes ou pour leur reproduction et développement suivant. Ceci implique aussi la résistance aux infestations ou aux infections, ou la réduction des pestes à un niveau limité pendant la période de croissance et production.

Mesures culturelles

Ceci implique des pratiques qui éradiquent les problèmes de peste en minimisant les conditions qui favorisent leur existence (eau, abri, et nourriture). Certains de ces facteurs sont intrinsèques pour la production de récolte, rendant l’environnement moins favorable pour la survie, la croissance, et la reproduction de l’espèce de peste. Le placement approprié des récoltes particulières dans votre jardin forêt peut réduire l’infestation des pestes. Si suivi d’une manière appropriée, les pratiques culturelles peuvent fournir un soulagement des pestes considérable.

Mechanical control

This is the use of tools to manually control pests. It involves agricultural practices like tilling, manual pest removal, and weeding. The pruning of infested parts of fruit and timber trees, and defoliation in certain crops help reduce pest populations. Chaffing of sorghum and maize stalks and burning of stubbles kills maize borer.

Sanitary control

Preventive practices are important part of an IPM program. These include cleaning field equipment (i.e., tillage equipment, haying equipment, pruning tools, etc.), planting certified seeds where possible, and quarantine or burning of infested crops or vegetation. These are methods used to prevent the introduction or reintroduction of a pest into the field.

Natural control

Natural control involves the enhancement of naturally occurring pest management methods to combat pests like crop rotation, and intercropping of plants that harbor beneficial insects or deter pests.

Chemical control

The therapeutic approach of killing pest organisms with toxic chemicals has been the prevailing pest control strategy for many decades. Safety problems and ecological damage continue to ensue from them, and there are renewed appeals for effective, safe, and economically acceptable alternatives. Synthetic chemical pesticides are the most widely used method of pest control, but they are also generally the most costly, and pose the greatest risk to the sustainability of your Forest Garden system and general environment. The four major problems encountered with conventional pesticides are toxic residues, pest resistance, secondary pests, and pest resurgence. We encourage the use of natural pesticides—often made from locally available, organic materials—that are more environmentally friendly where possible. We strongly recommend only using synthetic pesticides as a last resort, or only used as required and often only in limited amounts and at specific times in a pest’s life cycle.

Benefits and Disadvantages of IPM

Benefits of Integrated Pest Management

The benefits of Integrated Pest Management are immense, directly impacting Forest Gardens and the families who adopt them, and indirectly benefitting society.

It protects environment – through elimination of unnecessary pesticide applications, IPM is an environmentally friendly approach to pest control. In IPM, pesticides are only used when other methods of pest control have failed, and even then in very small doses. IPM measures are used in bringing a pest organism to acceptable bounds with as little ecological disruption as possible.
IPM improves profitability – since IPM approaches aim to apply the most economical pest management tactics, potential profitability is higher for the families who practice IPM.
It reduces risk of crop loss by a pest – applying pest management and monitoring tactics can ensure the reduction of crop loss or damage by effectively controlling pests.
It can lead to long term sociological benefits – long term benefits to society can also emerge from IPM in areas of employment, public health, and well-being of farmers, their families, and surrounding communities.

Disadvantages of Integrated Pest Management

In spite of the numerous benefits of IPM stated, there are also some drawbacks to it:

An IPM program requires a higher degree of knowledge and management – making the decision not to use pesticides on a routine or regular basis requires advanced planning and a higher degree of knowledge and management. This planning includes attention to field histories to anticipate what the pest problems might be, selecting crop varieties which are resistant or tolerant to pest damage, and choosing tillage systems that will suppress anticipated pest damage while giving the crop the greatest yield potential.
IPM can be more labor intensive – consistent, timely and accurate field scouting takes time. However, this information is the corner stone of IPM programs. Without this information you cannot make intelligent management decision.

Pest Prevention Measures

In all cases, it is preferable to prevent pests from attacking your crops rather than trying to control them once they do. The sections below describe the prevention measures you should take to decrease the risk of pests colonizing in your Forest Garden. In this section we will discuss characteristics and controls of certain general categories of pests and diseases which attack tree nurseries and fruit trees. Use the following sections to identify the problem encountered and determine a control method.

Disease Prevention

Disease control starts with prevention. When establishing fruit trees that grow slowly and may be producing for over 50 years, it is important to start preventative measures even before seeding in the nursery. Be especially careful at this stage because preventative measures taken at the time of planting may prevent a disease that could attack an orchard 5 to10 years in the future. Also, because diseases are not a onetime phenomenon and may take years to develop, preventative measures, especially sanitation, should be practiced routinely, not just applied at one time. There are three types of pathogens that attack plants and cause diseases: fungi, bacteria, and viruses. Fungi are the most abundant. They cannot manufacture their own food and are reliant on the host plants for survival. Fungi travel in the spore stage of their life cycle on animals, wind, water, and insects (vectors or carriers). Fungus diseases can be controlled by fungicides but often come back quickly, necessitating multiple applications. Diseases caused by bacteria are also very common. Bacteria also travel in a spore state on hosts to infect new plants. Like fungi they also do not manufacture their own food. Bacteria are harder and more expensive to control. Spraying trees with antibiotic is possible but not generally accessible to most farmers in the developing world. Most commonly the infected trees should destroyed. Viruses are the most serious type of disease. There is no chemical means for controlling them and infected trees should be destroyed. They are transmitted by sucking insects, especially scales and aphids, and by unclean tools such as knives, machetes, and other pruning tools. Resistant varieties are the only real control method for virus diseases. Here are a few simple preventative methods that you can use to prevent diseases before they infect your Forest Garden or nursery:

Physical preventative methods

Both fungi and bacteria live and thrive in humid conditions. One of the easiest ways to avoid fungus and bacteria caused diseases are to keep the Forest Garden dry. Build cuvettes (see section on cuvettes) so that the bases of the trunks of your trees remain dry. Pruning can also help. A well-pruned tree with air circulating throughout the branches will be much less likely to be attacked by these diseases. Avoid over-watering! If the trees are planted in clay soils that retain water, water much less than trees in well-drained soils. Try to plant only in well-drained soils.

Resistant varieties

Perhaps most importantly, try to find varieties that are resistant. If disease does attack, take advantage of this and identify trees which are unaffected for future seed sources. Never take seeds or vegetative planting material from diseased sources.

Sanitation

Most disease vectors can be washed off with soap and water. All tools, including baskets for harvesting fruit, should be washed with soap and water before each use. Household bleach or rubbing alcohol should be used on tools to kill viruses. If there is disease in the region you should collect your own fruit and take it to market yourself rather than having collectors from other sites harvest fruit from your own. If you are examining a disease in another farmer’s site, before to wash well before returning to your own or others! Wash yourself, wash your tools, change or wash your clothes. Diseases pass from orchard to orchard very slowly. Fifteen kilometers between two orchards may hold off a disease for years, but you can easily distribute it to your site or to others in one visit.

Sterilizing Soil

When propagating trees in areas where diseases are a problem, it is good practice to first sterilize the potting soil you will use for raising your seedlings and lining planting holes. Soil for nurseries and plantation holes can be sterilized using a simple 50 gallon drum method:

Remove the top of a metal, 50 gallon drum, and poke numerous holes through it;
Replace the top inside the drum on supports about 15 cm from the bottom;
Place the drum on three stones, at a height sufficient to light a small fire underneath;
Fill the drum with 10 cm of water, and fill your potting soil mix on the top placed inside the drum, to about 3 cm from the top of the drum;
Bury a potato about 15 cm deep into the potting soil in the drum;
Spread a thick layer of large leaves or sacks over the soil for insulation;
Start a wood fire under the drum and keep it stoked;
When the potato is completely cooked, the soil should be vector free.

Diversify and Rotate

Monocultures are one of the most common ways to transfer diseases across your entire field. This, of course, is not a problem in Forest Gardens. However, it is even good practice to diversify the varieties of fruits and other trees you plant in your Forest Garden. If you are planting a lot of mango trees, for example, mix up the varieties and mix up the rootstock seed sources. For citrus however, resistance to diseases comes only from using proper rootstock which is disease resistant. Best yet, plant many types of trees, fruit and otherwise, in your Forest Garden. Plant certain varieties in rows with other types of trees between the rows. This way harvesting is still easy yet variation is kept high. One easy thing to do is to put large thick cashew windbreaks throughout the orchard, though sometimes cashew trees harbor mango pests. If planting short lived fruits (e.g. papayas, bananas, and pineapples) do not plant them in the same spot after removing the previous crop. Instead, rotate in different trees or other crops. It is also a good idea to rotate nurseries. In an area where there was a mango nursery the previous year, this year raise citrus or let it go fallow.

Vectors or Pests

As mentioned above, diseases, especially viruses, have no way to move between host plants on their own. As these pathogens spend some of their life cycle in vectors (carriers of the disease), a good way to control diseases is to control the vectors. Scale insects and thrips are perhaps the most infected insects we deal with, but general sucking insects, nematodes, flies, and even the beneficial bee may be carriers of disease. Read the pests section below to learn more.

Keep your trees healthy

Trees have natural defenses against diseases. Weak, sick, or damaged trees may quickly succumb to normally harmless diseases. Lack of water or nutrients, failure to prune dead, damaged, diseased, and disruptive branches, and damage caused by careless pruning, can severely weaken a tree and make it susceptible to diseases. Read the pest sections below to find out how to control these.

Pest Prevention

Because pests are such a diverse and unpredictable problem, only so much can be done in advance to prevent infestation. With some pest types, though, preventative measures do exist and should be employed when the pest is known to be in the region:

Sanitation

As in diseases, pests thrive in unclean or unkept areas. Any dead or diseased plants or parts of plants should be removed from the plantation. Dead plant material is a breeding ground for pests and a feeding ground for termites.

When traveling from sites with pest problems, take care not to transport any pests or eggs. Any vegetative matter or soil which is exchanged between sites should be completely cleaned before arriving to another site. Fruit which may contain scales or fly eggs should not be brought to non-infested sites.

When pests are a problem, sterilize soil as described above to destroy all eggs, nematodes, and larvae living there.

Plant resistant species

This is much more difficult with pests than it is with diseases. Some species may be found which are resistant to pests such as nematodes or taste bad to pests such as caterpillars.

Weeding

Keep weeds cleared from in and around your cropping areas and permagarden. Weeds can host pests that will attack your crops.

Termites

Termites are a big problem in the dry tropics. Preventative measures should be taken early on in tree development to control these pests. Despite local rumors, few termite species live off living tissues. They mostly only attack dead wood. The species that do attack living trees, however, are present in some parts of Africa. These species rarely kill adult trees and actually do little harm to healthy trees. When a tree is being attacked and killed by termites it is usually a sign that something else is wrong. Termites can do severe damage, however, and may even kill many seedlings or young trees. A couple of preventative measures can be taken to help alleviate the termite problem:

Wood ash – mix wood ash in with the soil in the nursery and the transplant hole. Wood ash is very abrasive and termites do not like to crawl through it.
Neem leaves – add neem leaves or neem seed cake to soil mixtures in the nursery, and periodically at the outplanting site.
Removal of dead wood – because termites feed mainly on dead matter it is important to keep large amounts of dead wood clear from your Forest Garden and nursery site. After pruning a tree gather up all the cut branches and use them for fuelwood them or take them away, to harbor termites elsehwhere. If you have a dead fence to protect your growing living fence or nursery, keep it a suitable distance from the trees and keep the area between the two clean.
Mulch – keep the soil rich in organic matter and covered with mulch. The termites that do remain will feed on this dead plant material and not your trees.
Build cuvettes – Fruit trees love mulch and love periodic additions of manure. Yet these two substances attract termites. By building a cuvette, and adding mulch and manure to the cuvette instead of at the base of the tree – thus keeping the area at the base of the tree clean – the tree trunk will avoid direct exposure to termites.

Nematodes

Nematodes, another very common pest problem, can also be controlled or avoided completely by preventative measures listed here:

Sanitation – soil sterilization should be done in nurseries if nematodes have been a problem in the past (see soil sterilization section above). Burn any infected plants.
Plant resistant varieties – some varieties have built up natural defenses to nematode attack. Plant resistant varieties wherever possible.
Intercrop with marigolds – marigold roots repel nematodes and can be easily planted at the beginning of the rains with very little effort. Plant them on the bunds surrounding your permagardens and disperse them in beds and other parts of your Forest Garden among plants susceptible to nematode attack. Most marigolds are prolific seeders, so the seeds collected from dead flowers can easily be replanted.
Crop rotation – one of the best ways to avoid continuous nematode infection is rotate crops susceptible to nematodes, never planting them in the same place continuously (see crop rotation in the intercropping section). Bananas and papayas, which are short lived but especially sensitive to nematodes, should never be planted in the same location after removing, nor in a location where there were other nematode-attracting vegetables or fruit trees.
Enrich your soil – Natural enemies of nematodes are present anywhere nematodes exist. These natural enemies are generally present in health soils enriched with organic matter. Add mulch and manure to cuvettes and keep the soil around trees healthy and full. This will also help the tree stay healthy so that its own defenses can protect it against nematode attack.

Pest Control Measures

Using preventative measures when establishing trees in your Forest Garden, you will avoid many of the common and more serious pest and disease risks. Unfortunately they can still attack your crops even when all precautions are taken, and oftentimes farmers already have some existing trees on the Forest Garden site, some of which may already host some type of pest. It is understandable when problems arise that you may prefer treating these pests with proven chemical treatment rather than experimenting with natural treatments, and we do discuss chemical options for managing pests and disease below. As chemical treatment can diminish the overall integrity and health of your Forest Garden, however, we strongly recommend using chemical treatment only as a last resort. There has been an emphasis in research on natural and organic pest control methods over the past decade, but unfortunately little has been suggested about organic or biological control of diseases. This is because, as mentioned above, there are few organic methods to destroy disease pathogens other than simply destroying the infected tree. At the same time, even if cures are available, the diseases or pests need to be correctly identified first in order to use the correct treatment, which may not be easy. Figuring out what pathogen, pest, or combination thereof is causing certain symptoms often requires experts that are typically not present or accessible in most places. Although tricky, disease and pest identification is possible to an extent that can be adequate for most cases. The first step of the IPM process, when an undesired or unnatural symptom exists and is persistent or spreading on or between trees, is to look for and identify a pest. Pests, because of their physical presence, are much easier to diagnose and treat than diseases. Sometimes a pest will be too small to see or will not be present (leaf borers are located inside stems, cut worms only come out at night) so the absence of a visible pest does not immediately mean a disease is present. If the pest is not present ask the following questions about the symptoms of the disease or pest:

Are the symptoms general all over the plant or localized in one area?
What parts of the plant are affected? What part of the plant was first infected? Is the disease spreading?
What are the characteristics of the symptoms? Wilting? Large brown spots? Discoloration? Rotting? Death of part of the plant? Cancers? Perforations? Cuts? Dropping of young fruit? Presence of gum or resin?
What time of year do the symptoms appear?
Is the damage serious enough to require treatment?

After you answer these questions, try to use the following general descriptions to try to identify the problem. If the symptoms do not match up or you still do not feel confident, try to get an expert or extension agent knowledgeable on pests and diseases in your area to help you identify the cause.

Diseases

Although chemical controls may be available, as we have said time and again, we do not encourage their use unless the disease is accurately identified and all other forms of control have been exhausted. Remember that the best way to combat disease is by taking precautions in disease prevention from seed selection to nursery care to outplanting and managing of trees. Keep your trees healthy and control pests which carry disease. However, when symptoms of disease do arise, use this section that describes some of the most common diseases as a reference and foundation from which further investigation can be done. FUNGUS DISEASES Fungi can live on the surface or inside the host plant. Powdery mildews and root rots are caused by fungi which live on the surface of a host plant. Fungi can also live inside the host and erupt in the form of downy mildews, leaf spots, blight, rusts, anthracnose, and scabs. Fungi can also remain completely inside the host causing “wilts”. Preventative Measures: Avoid creating humid situations in the nursery and orchard. Build and maintain cuvettes around high-value trees to avoid water-logging roots and trunk. Avoid over-watering. Plant trees only in well-drained soils. Do not water every day in soils which do not drain well. Adhere to spacing requirements to allow aeration between trees. Use resistant varieties when applicable. Organic control: Prune and burn all infected areas. Chemical Control: Spray fungicides. Anthracnose is probably the most commonly found fungus disease. It plagues the mango although it may also attack citrus, avocado, annona spp, and other species. Generally anthracnose is spread by fungi. The symptoms appear to be very similar for all species. It seems to attack branches, leaves, fruit, and sometimes young roots, and eventually leads to death of the tree. When it attacks mangos the extremities turn brown and the roots may dry up. Leaves have small, round spots dark brown to black in color or holes which may appear in leaves in place of the spots. Leaves will also fall off the tree. Fruit will have small dark spots, especially young fruit. The disease can also manifest itself as cankers on leaves, roots, and fruit of citrus, annona spp., papaya, and avocado. Possible Control Measures: For all species, prune and burn all infected branches, leaves, and fruit. Spray infected areas with fungicides. Damping off occurs in the nursery when fungus disease attacks germinating seeds. This is often a problem with citrus. Preventative Measures: Avoid excessive watering in the germination bed or after seeding tree sacks. Be sure the germination bed or sacks are well-draining. Treat the seeds with ash before sowing. Possible Chemical Controls Fungicides. Cercospora appears as cankers on leaves and spots on fruit. Like anthracnose, its pathogen is usually fungi. The treatment is generally the same as with anthracnose. Possible Control Measures: For all species, prune and burn all infected branches, leaves, and fruit. Root rotting caused by Phytophtora spp. is common in many places. It attacks many species, although it is most commonly found on citrus, pineapple, papaya, and avocado. Fruit becomes discolored, leaves dry out and fall off tree, and roots are destroyed. Possible Chemical Controls: Spray with fungicides. BACTERIAL DISEASES Bacteria spores are transported by wind, water, animals, insects, and humans. Bacteria can feed off of living or dead tissue. They multiply in the host plant by rapid cell division. Gummosis is the most common and most serious bacterium spread disease of citrus. It attacks the roots and trunks of trees. Leaves turn yellow, become brittle, and fall off. The most obvious symptom is the gum being excreted from the tree, usually along the lower trunk and roots. It will lead to the eventual death of the tree. Preventive Measures: Using resistant rootstock, planting in well-drained soils, and making cuvettes are especially important to combating gummosis. Possible Control Measures: Cut off infected areas and paint with flint coat VIRAL DISEASES These diseases cannot be prevented nor controlled by spraying. They are transmitted by sucking insects. By controlling these insects you are indirectly controlling the disease (see “sucking insects” below). Viruses are not visible to the naked eye and can only be seen through an electron microscope, therefore they are known by the symptoms they manifest. Preventative Measures: For citrus, use resistant rootstocks. Tristezia is a disease which attacks citrus grafted on non-resistant rootstock. The disease causes “die back” from the twigs inward and results in death of the tree. Early prevention in anticipation is good planning for citrus growers. Preventative Measures: Grafting onto resistant rootstock and controlling sucking insects are the most important ways to avoid this disease. Possible Control Measures: The only way to control tristezia is to destroy the infected trees. Exocortis stunts the growth of the tree by causing slow growth and incompatibility between the budwood and rootstock. Preventative Measures: Use resistant rootstock. Possible Control Measures: Destroy infected trees.

Pests

There are basically three types of insects which attack plants: sucking insects, chewing insects, and borers. SUCKING INSECTS Sucking insects have modified mouth parts which include a long straw-like appendage that they insert into plants to suck out juices. They can attack the leaves, bark, or fruit of the plant. Large amounts of these insects can weaken a plant or lower a plant’s yield. They are also the principal carriers of plant diseases. The first and most obvious symptom of sucking insects are the insects themselves. Sucking insects are usually controlled by contact poisons, which can be made organically from locally available ingredients. Types of Sucking Insects Scales or mealy bugs will be the most obvious because they do not move or move very slowly. They appear as either black or white spots or bumps on the plant surface. They usually appear on the stems or branches, but are also found on leaves, buds, and fruit. They have either a hard, or cotton-like appearance, almost resembling tiny oysters or seashells in some cases. Scales live in colonies. Once one is spotted others you can be certain that others are nearby. Sometimes scales live in symbiosis with ants (scales suck the juices out of the plants and the ants feed on undigested sugar excrement from the scales in return for protection from possible carnivores). Scales attack almost all fruit trees commonly planted in Forest Gardens, especially citrus and mango species. Scales are considered the dirtiest pest because they are well known to be carriers of viral diseases. They can weaken plants and lower the quality of the fruit. Organic Control: Because there may be so many of them, scale insects are difficult to control. Physically removing them is possible but can be laborious. Try using a cotton swab dipped in alcohol to touch each insect. Spot spraying the trees with a mixture of peanut soap and water will also kill scales. Since scales often live closely with ants, a method for controlling scales is to control the ants. The ant species which live with scale insects live on the ground and are forced to use the trunk of the tree as transport to and from the scales. Applications of anti-ant compounds around the trunk can be useful. Aphids can be too small to see with the naked eye. Aphids reproduce very quickly and live in colonies. Although one of these pests may not be able to do much damage, a colony can severely damage a plant. They often discolor plants at the site of attack. If leaves are turning gray because of many tiny holes on their surface (silvering) aphids may be the cause. They also cause distorted growth like bent or twisted branches and leaves. They can also attack and lower the quality of fruit. As with scales, aphids ants will often be observed alongside aphids. They secrete honey dew which they process from the plant’s juices, and the ants eat the honeydew in exchange for protection. Aphids may carry diseases. They usually are active during the plant’s growth phase. Organic Control: Spot spray with a clay/water solution or annona spray. Control the ants (see scales above). ** Note on scales and aphids – natural enemies can be used to keep these insects under control in your Forest Garden. Often when orchards are treated with insecticides, the enemies are killed rather than the scales and aphids, resulting in a sudden increase in their numbers. For this reason among many others, pesticides should only be used as a last resort and then should be spot sprayed. Another way to control aphids and scales is to control the ants by applying anti-ant compounds at the base of the tree. Thrips are the third economically important sucking insect. Thrips are generally too small to see with the naked eye. They may also cause silvering of the leaves and fruit; sometimes infected leaves may roll up. They also are carriers of virus vectors. Organic Control: Neem oil can be used to spot treat heavily infected areas. Smothering a solution of soap and water on the leaves and stems of heavily infected areas may be enough to dehydrate and kill them. CHEWING INSECTS Chewing insects actually eat the plant parts, usually attacking the leaves of the plant. These are usually not a problem for mature plants unless there are a huge number of these insects, as in the case of locust swarms. Chewing insects are a problem in nurseries and germination beds, however. They can completely defoliate seedlings quickly. A seedling that loses all its leaves will be weakened considerably and will take a long time to heal. Often seedlings in fields (cashews, for example) after being attacked by defoliating chewing insects are very susceptible to termites and are destroyed by a combination of these two pests. Most caterpillars and grasshoppers are chewing insects. Caterpillars are young butterflies or moths. They are easily visible on plants; their primary symptom is leaf damage. Look for the small white eggs often found on the underside of leaves singly or in clusters. Organic Control: Touch the caterpillars with a rag soaked in kerosene or hand pick them off by looking for damaged plants. Bring a chicken along for a free meal! Cutworms is a common name given to a group of chewing insects that come out at night. One type of cutworm cuts off seedlings right at the collar, killing the whole seedling. Another type will climb the trees and eat the leaves; they eat irregular holes into the leaves starting with the edge. Organic Control: Identify the infected plants during the day, then go out at night with your flashlight and hand pick the insects. Try cutting the top and bottom off a large can of tomato paste and putting it around the base of the seedling. You may also dig around the soil of plants showing symptoms to find the cutworm sleeping. Leaf miners can be identified by clear lines on the leaves of the plant. They are rarely an economically important pest. Organic Control: Prune and destroy affected leaves or dust the leaves with wood ash. BORING INSECTS Borers are insects that bore inside the plant stem, root, or trunk. Borers can destroy seedlings, plants, and young trees by completely cutting off their stem. If their populations grow uncontrolled they could be a problem for Forest Gardens and permagardens. Symptoms of a borer insect are spot wilting of the infected branch or plant, and a small hole where the insect entered the stem. Boring insects can cause a lot of damage for annona species. Control: Prune infected tree branches about 25 cm above the borer’s hole. If the branch at the prune site is hollow, prune further up. Destroy the borer. FLIES There are some species of flies that lay eggs in fruit, thus destroying the fruit, and some that have maggots that eat plant tissue. Fruit flies are the most economically important as they may be able to attack fruiting trees in your Forest Garden in great numbers and destroy that fruit’s harvest. Small yellow stains with a black spot in the middle on a fruit is a sign eggs were laid. Later the fruit will have localized rotting, cavities where the maggot eats on the inside, and may drop off early. Organic Control: Make poisonous bait traps to catch the flies. Mix two teaspoons full of household ammonia and 1/4 teaspoon of soap powder in a quart of water. Fill a jar with the mixture and put the jar right next to the sunny side of the plant. This bait should be changed once a week. Also destroy any affected fruit. Physical Control: Collection and disposal of fallen infested fruits and the infested soil should be removed. Undersized fruits left on the tree should be picked and destroyed. If the trees are few in number, bagging the fruit with cloth or paper bags can be resorted. ANTS Ants may use the plants in your Forest Garden as homes (the red ant on mangos and oranges, for example), or cause indirect harm to the plant by protecting other insects such as scales or aphids. Red ants may not cause any direct damage to the tree except for damage to the leaves at the nest site but can cause discomfort when the tree is worked on or harvested. These need to be controlled because if left unchecked the ant will reproduce until the trees are completely overtaken. Control is simply finding, cutting down, and burning the nests.

Non-insect pests

Mites are tiny animals, often invisible to the eye, which suck the juices from plants much like aphids and scales do. Mites are related to spiders and thus are not technically insects. They cause silvering of the leaves and fruit by the millions of tiny “bites” they leave. They can weaken trees and lower the quality of the fruit. One species, which attacks citrus, appears as tiny red dots on the underside of leaves. Look for leaves on citrus which have small light spots on the top; turn the leaf over and look for the mites. Organic Control: Try spot spraying with a soap and water solution. Nematodes are microscopic worm-like parasites that stick their heads into roots and suck out plant juices or live entirely inside plant roots. They can cause general tree wilting, small production of fruit, small sized fruit, and stunted growth. To confirm the presence of nematodes dig up the roots of the infected plant and look for the “nodes” (small bumpy swellings). Organic Control: Crop rotation. Sterilize the soil. See Nematodes section under Pest Prevention Measures above Snails can be a problem during the rainy season in nurseries. They eat the leaves of young plants and can completely destroy them. Organic Control: Use sunken bowls filled with beer as traps. Trenches a few centimeters deep made around the nursery and filled with wood ash will prevent snails from entering. Adding salt in trenches, or put directly on the snails will kill them.

Diseases and Pests Common to Permagardening Crops

This section lists some common pests that you may encounter in your permagardens, along with some recommended control measures. White Fly

Indication of Presence: fly around when disturbed, make honey dew
Plants Affected: beans, brassicas, cucurbits, okra, , Solanaceae
Habit: underside of leaves
Damage: Sap-feeding weakens plants, transmits viruses
Controls: remove infested plants/leaves, sticky traps, insecticidal soaps, neem oil, hillbilly breath

Mealy Bugs

Indication of Presence: Mealy bug colonies
Plants Affected: Sweet potato, water spinach, papaya
Damage: Deformation of new growth, reduced yield, death of plant
Habit: Underside of leaves, new growth
Controls: Good cultural practices for plant vigor, beneficial insects, physical removal

Leaf Miners

Indication of Presence: White tracks in leaves
Plants Affected: Cucurbits, okra, , Solanaceae
Damage: Reduced photosynthesis, reduced yield
Controls: Remove infested parts

Fruit Flies

Indication of Presence: Holes in exterior fruits, maggots in interior, deformation or rotting around the portion of the fruit infected
Plants Affected: Cucurbits Solanacea, beans, Papaya
Habit: Vegetable Fruits
Controls. Remove dead fruit, Hillbilly breath

Pepper Maggots

Indication of Presence: Peppers begin to form translucent brown patches
Plants Affected: Hot pepper, green pepper
Habitat: Maggots – peppers, Flies – leaves
Controls: Destroy fallen fruit, crop rotation, Hillbilly breath

References

The information found in this chapter is largely taken from C.O. Ehi_Eromosele, O.C. Nwinyi and O.O. Ajani. INTECH. Chapter 5: Integrated Pest Management. 2013. http://cdn.intechopen.com/pdfs-wm/42758.pdf

Updated on mars 1, 2018

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