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 Pests and Diseases in Horticulture  Level II Agricultural Business Operations Session 10.

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Presentation on theme: " Pests and Diseases in Horticulture  Level II Agricultural Business Operations Session 10."— Presentation transcript:

1  Pests and Diseases in Horticulture  Level II Agricultural Business Operations Session 10

2  Acknowledge information and pictures from  Top Fruit Diseases  Apple Scab  Apple Canker  Powdery Mildew  Crown Rot  Top Fruit Pests  Red Spider Mite  Aphids e.g. Green fly, woolly Aphid  Caterpillars e.g. Codling Moth, Blastobasis

3  Soft fruit Diseases  Phytophthora  Botrytis(Grey Mould)  Powdery Mildew  Horticulture pests  Vine Weevil  Leather Jackets  Carrot Fly  Slugs

4  Acknowledge information and pictures from above website

5  Fungus overwinters within the tissues of infected leaves and ascospores develop in early spring.  Scab also overwinters on bud scales so infecting young leaves as they emerge in spring  Another source of infection is lesions within the wood which have resulted from infections the previous year


7 Temp (C) Temperature (F) From Primary Inoculum Apr-Jun (Ascospore) Hours of leaf wetness From Secondary Inoculum May-Oct (Condia) Hours of leaf wetness Days required for lesions to appear 948151017 105014916 115212815 135511714 57106.513 16-2461-759610

8  Routine control of apple scab through fungicide application during the spring and summer period is essential for business success in commercial apple production.  The optimum interval between fungicide application, and thus the total number of fungicide applications during the production cycle depends on prevailing weather conditions, and the associated incidence of Apple Scab Infection Periods (ASIPs).  In Northern Ireland, the incidence of ASIPs is assessed using meteorological data from AfBI, Loughgall.

9  Apple canker is an economically important disease of apple  The fungus attacks twigs and branches, causing cankers and dieback in mature trees, and often death of young trees.  It also attacks fruit causing rots both in the orchard and in store.  Losses due to canker are difficult to estimate, but those of 10% or more in young trees in newly planted orchards are typical and, in seasons favourable to the disease, losses due to rots in stored fruit can be as high as 30%.  The fungus is not specific to apple and attacks pear and quince and several forest and hedgerow trees including beech (Fagus), poplar (Populus), hawthorn (Crataegus) and Acer.  These other susceptible species could therefore act as a source of Nectria inoculum. In practice only poplar has been implicated in canker outbreaks in apple orchards.  The disease is present in virtually all the apple producing areas of the world  Its prevalence as canker or fruit rot is dependent on seasonal rainfall patterns.


11  Control  Spring Summer spray programme  Autumn spray programme (Copper Spray at 5% and 50% leaf fall)  Remove prunings from the orchard  Cut out/prune out cankers from the tree

12  Powdery mildew is an important disease of apple. All the main UK culinary and dessert varieties are susceptible, especially Cox and Jonagold.  The fungus overwinters as mycelium in fruit buds or vegetative buds which emerge as primary mildew i.e. mildewed blossoms at pink bud or mildewed shoot tips at petal fall.  During spring and summer mildew spreads from the primary mildew sources to developing shoots (secondary mildew epidemic) and under favourable conditions can infect leaves and produce sporing mildew colonies in about 4‑5 days.

13  Primary blossom mildew  Mildew colonises fruit buds in early summer (about June) and colonises vegetative buds at the end of extension growth in late summer, where it remains quiescent until the following spring.  Symptoms are readily recognised on shoot tips, leaves, blossoms and fruit.  Mildew inoculum level is the key factor in determining the seasonal epidemic. Managing the mildew epidemic through careful watching of disease incidence is essential to rationalise fungicide use and to check that control measures are effective.


15  Crown rot and collar rot are distinct diseases.  Collar rot is a disease of the scion which usually only attacks mature trees >10 years old.  Crown rot a disease of the rootstock which, in the UK, is mainly a disease of young trees in the first two years of establishment.  Susceptibility of varieties and rootstocks varies, with Cox, James Grieve, rootstock MM.106 being the most susceptible.  Both diseases are caused mainly by Phytophthora cactorum and are favoured by wet weather. P. cactorum is soil borne and can overwinter and survive in the absence of apple as oospores (resting spores). These germinate to release zoospores which move in soil moisture to infect the roots/root crown or scion through cracks, damage or lenticels.  The first symptoms of crown or collar rot may be poor growth, leaf yellowing or premature autumn colours.  In the rootstock below ground the presence of typical orange/red-brown rot under the bark is characteristic of crown rot.  A water-soaked, weeping area on the trunk which has a distinct orange/red-brown rot under the bark is characteristic of collar rot.


17  Fruit tree red spider mite has a simple life cycle, overwintering as eggs on the bark, mainly around fruiting spurs. Eggs hatch in late April to mid June, around blossom time of apple. Young mites then invade the leaves and trusses.  There are five or six successive generations of adults, mainly on the undersides of leaves, before eggs are laid on bark in the autumn. The generation time is about 4 weeks with 3 moults.  The pest is seldom a problem in orchards where the orchard predatory mite Typhlodorums pyri is established and encouraged. It is important to regularly monitor levels of the pest and the predator.  The presence of high populations of fruit tree red spider mite which causes bronzing of foliage (yellowing leaves with brown speckles) and fruit russeting is an indication of failure of proper integrated mite management. The predatory mite should be introduced, by transferring summer prunings in summer to newly planted orchards and to orchards where it is absent.  Pesticides harmful to the orchard predatory mite should not be used except as a last resort, as they cause outbreaks of rust and spider mites.


19  Apple- Grass Aphid  Green apple aphid  Rosy apple aphid  Rosy Leaf-Curling Aphid  Woolly Aphid

20  Symptoms  The Larva leaves a prominent, red-ringed entry hole in the side of the apple blocked with dry frass.  Description  Adult 20mm wingspan. Forewings are grey with coppery coloured tips. 5 pairs of prolegs  Life Cycle  First generation adult moth flies in June/July. Mating occurs at dusk when temp >14 degrees. Eggs are laid singly on fruitlets. No. of eggs laid increases with temperature. They hatch10-14 days later and the larvae enters the apple where it feeds for 14-18 days passing through five instars. The larvae leaves the fruit and spins a cocoon to overwinter under loose bark then pupates in the late spring. In hot summers, cocoons may pupate in late July producing a second generation in Aug/Sept.  Assessment  Pheromone traps attract males. Threshold is 5 moths/trap/week in 2 out of 4 weeks  Control  Apply insecticide10-14 days after threshold catch to coincide with the onset of egg hatch



23  Symptoms  Bramley and short stalked varieties susceptible. Damage on fruit as deep surface grazing and internal mining. Fruits in clusters are most prone to attack, damage occurring where adjacent fruit touch. A sticky mass of black frass is produced.  Description  Adult is straw coloured with 20mm wingspan and each wing having 4 darker spots.  Life Cycle  Adults emerge from June and lay eggs on leaf and flower debris. Larvae emerge 7 days later and feed extensively beneath dead leaves around the stalk of maturing fruit.  Pupation occurs in Sept in small cocoons amongst debris where the insect overwinters on the ground.  Assessment  No pheromone traps are available at present. Low levels of damage at harvest should prompt treatment the next year.  Prevention  Regular use of broad spectrum pesticides as soon as caterpillars or damage are seen.

24  Caterpillars are the larval stage of various butterflies and moths. There are several species of caterpillar that feed on brassicas leaving holes in the leaves and hearts of cabbage, other brassicas and other plants including turnip, swede, horseradish and nasturtiums.  Large cabbage white butterfly caterpillars are yellow and black with obvious hairs on their bodies.  Small cabbage white butterfly caterpillars are pale green and covered in short, velvet-like hairs.  Cabbage moth caterpillars are yellowish green or brownish green, with no obvious hairs on their bodies.


26  Vine weevil is a beetle that attacks a wide range of plants, both indoors and outdoors, but especially plants grown in containers.  It is one of the most common and devastating garden pests. The adult weevils eat plant leaves during spring and summer, but it is the grubs that cause the most damage over autumn and winter when they feed on plant roots, causing wilting, and often plant death.  Plants growing in pots or other containers, outdoors or under cover, can be severely damaged by vine weevil grubs. Plants growing in the open ground are less susceptible, although the grubs can kill strawberries, primulas, polyanthus, Sedum, Heuchera and young yew plants.  The adult beetles feed on the foliage of many herbaceous plants and shrubs, especially Rhododendron, evergreen Euonymus, Hydrangea, Epimedium, Bergenia, Primula and strawberry.  Symptoms – The larvae feed on the roots of plants so the first indication of anything wrong could be the collapse and death of the plant. Adult vine weevil will feed on the leaf of many different plant species.

27 Larva (grub) – soil living Adult Weevil – above ground

28  Slugs and snails will eat most parts of vegetables and herbaceous plants, with the young growth in spring particularly vulnerable. Slugs will also eat seeds and tubers, and maincrop potatoes are often badly damaged. They are most active at night and in humid conditions.  Symptoms – Irregular holes in leaves and other parts of the plant. Slime trails can be seen on soil and hard surfaces.

29  Soil borne Phytophthora Diseases  Affected plants do not thrive, and later wilt. Red Core is caused by the fungus Phytophthora fragariae. When the main roots are cut longitudinally the stele is a distinctive dark red/brown.  Crown rot is caused by Phytophthora cactorum. Affected crowns have distinctive markings when cut in half.  Both these diseases can come in contaminated runners so runners should either be drenched before planting or sprayed with a fungicide after planting.

30  Powdery Mildew  Powdery mildew is the most serious disease of table top strawberries under cover. A preventative fungicide programme is most important. Mildew is exacerbated by high humidity, so is usually more severe towards the end of the season. Tunnels with poor drainage or over watering, and which have standing water on the ground are the worst affected. Infection is mainly from spores which overwinter in the tunnel. If mildew is well controlled in Autumn, fewer spores overwinter to cause trouble in the new season.  Development and spread of powdery mildew is temperature dependent. Infection can start slowly in cool spring weather and may be seen by carefully observing leaf roll, or checking with a hand lens on the under surface of leaves for early mycelium. If not treated at this stage it can rapidly become severe as temperatures rise.

31  Control in soft fruit  Protectant sprays applied 7-10 day intervals early in the season or when humidity and risk are low, or every 7 days in the season or when humidity is high. Good coverage, especially of underside of leaf where infection enters.  Sulphur is an economical way to control mildew. Resistance does not develop to sulphur in the way that it does to synthetic fungicides. It can be applied as a spray or by sulphur burners. Such burners are most suited for use under glass. A drawback is that they weaken polythene, so use should be restricted in polytunnels. Flowable Sulphur is more convenient to use than wettable powder.


33  Most infection is at flowering, with the fungus lying latent for a period. Increased humidity and sugar availability makes the latent infection active. When it appears in the ripening fruit, direct infection to new fruit then occurs. The disease overwinters on dead material around the crown. One function of the late winter clean up of the old plant material is to reduce the carry over of Botrytis  Fungicides include Systhane, Topas, Signum, Amistar, Fortress, Corbel, Kindred, Potassium bicarbonate.

34  Aim for a water volume of 1,000l/ha to give good coverage of table tops.  A fine spray is most effective. Check nozzles.  Impurities in water make chemicals less effective. Rain water (filtered) gives the best results. Mains water is usually preferable to bore hole water for spraying. The latter tends to have more dissolved salts and is sometimes contaminated with bacteria.  Note: Always read the product label. Use pesticides safely. If applying a product under an EAMU (Extension of Authorisation for Minor Use) you should be familiar with the terms of use and keep a printed copy of same for your records.


36  Leatherjackets are the larvae of crane flies. They are soil inhabiting pests that mainly feed on roots and the underground parts of stems of crops.  Biggest population in a field going into crop from grass  Life cycle is eggs hatch in Aug/Sept with the larvae feeding until May. Larvae pupate near soil surface in May with adults emerging in Jun/July. Adults do no direct damage.


38  Carrot fly is widespread pest of carrots with the larvae feeding on roots of carrot. The larvae can kill young plants and leave larger plants unmarketable. The fly does not travel far.  First generation carrot flies emerge in Apr with eggs laid in May. Larvae feed and pupae are formed during Jun/July. Adults emerge from July onwards to produce overwintering generation which continue to feed on overwintered crops.

39  Non chemical control  Crop rotation  Time of sowing  Mesh covering  Monitoring with yellow sticky traps

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