Monitoring, prevention and control of plum moth (BIOFRUITNET Practice Abstract)

Pheromones used for Grapholita funebrana are not species-specific, and usage of pheromone dispenser lures will attract other Grapholita species including Grapholita molesta (Oriental fruit moth), causing similar damage. Practical recommendations • HOST PLANTS: Larvae can cause significant damage on main host plants as plums (Prunus domestica) and apricots (Prunus armeniaca). In addition, peaches (Prunus persica), almonds (Prunus amygdalus) and other Prunus species are also attacked. • LIFE CYCLE: usually two generations per year • 1st generation: May to June • 2nd generation: July to August • In climatically favourable regions, a third generation may emerge around mid-August before the adult caterpillars of the last generation visit the overwintering sites. • DAMAGE: o 1st generation: Female moths lay eggs singly or in small groups on fruitlets. Entrance holes, however, are barely visible. Larval feeding causes gummosis, exuding fluid from the entrance hole. These are good detections for diagnostic observation. A premature colour change from green to violet and/or fruits drop. o 2nd generation: Females lay eggs in maturing fruits, and larvae feed throughout the fruit, travelling from the outer part to the stone region, forming filled tunnels and feeding inside. Usually, only one caterpillar develops per fruit. Fruits are inedible, unmarketable quality. • CONTROL AND PREVENTION: Use mating disruption with the pheromone dispensers Pheromones to monitor G. funebrana can be placed in the same traps with pheromones of Cydia pomonella o Placing sex pheromone dispensers along the edges of fields, rather than in the centre, is recommended o Pheromone traps are not species-specific, catching many other Grapholita species, including males of G. molesta o Late-maturing varieties are more damaged, early ripening varieties should therefore be grown. o Direct control by the application of products based on Bacillus thuringiensis ssp. kurstaki onto the fruits at the peak of larvae hatching

Strategy to control Plum Pox Virus damage (BIOFRUITNET Practice Abstract)

Growing PPV-resistant varieties combined with PPV-resistant rootstocks improve fruit-growing economics and financial return. Practical recommendations • HOST PLANTS: All stone fruit species, PPV mainly infects plum trees. Apricots, peaches, nectarines, and sweet and sour cherries can be infected by different strains of the virus • SYMPTOMS of the Plum Pox Virus disease: o On leaves: Ring-shaped chlorotic spots and marks, mostly diffused, bright green o On fruits: Deformations, ring-, line- or pox-like depressions or shrivelling fruit • DAMAGE: o Fruits have lower sugar content, worse appearance, and are unsuitable for fresh sale consumption o Fruits fall prematurely to the ground, and fruit quality and yield is lower o Infected trees have lower assimilation due to chlorotic spots, and tree vigour is lower DISEASE TRANSMISSION: o PPV damage occurs mainly after planting of infected plant material, and the virus is spread by aphids in orchards o Vegetative, especially by vegetative reproduction (scions, grafts) o PPV can also be spread during tree pruning through non-disinfected pruning devices • PROTECTION: Treatment against PPV does not exist yet, so the application of preventive measures is the only effective way of disease control. Direct control only reduces the next virus spreading o PREVENTIVE MEASURES: Use certified virus-free plant material, and grow resistant varieties grafted onto resistant rootstocks to fully protect trees against PPV infection o DIRECT MEASURES: Destroy all infested trees and control aphids (the vector of PPV transmission) for the purpose of decreasing the additional spreading of PPV within the orchard • PPV-resistant plum varieties: Jojo, Jofela, Joganta, Jolina, and Moni • PPV-resistant plum rootstocks: Docera 6, and Dospina 235 • Growing resistant varieties on resistant rootstocks avoid PPV infections in plum orchard

Strategy to control Little Cherry Disease (BIOFRUITNET Practice Abstract)

Cultivation of varieties that are less sensitive to LChV will give a stable yield of high quality and good flavour sweet and sour cherry fruits. Practical recommendations and information • Two causal viruses exist: Little cherry virus-1 (LChV-1) and Little cherry virus-2 (LChV-2) • SYMPTOMS can look like: o Fruits are small, triangular, flattened, leathery peel o Poorly coloured, tasteless fruits o Reduced sugar content o Premature reddening of leaves o Lower tree vigour, lower tree volume o Plants can be infected without any visible symptoms (often on ornamental species) • HOST PLANTS: o Species of Prunus genus, mainly sweet and sour cherries, including ornamental species o Infections on apricots, peaches, plums and almonds have not been recorded yet • Virus-infected trees cannot be treated; treatment options against LChV do not exist yet, so only the application of preventive measures is effective • Vegetative virus transmission is possible, especially with infected planting material and with vegetative propagation (e.g., scions, grafts) • LChV-2 virus is also transmitted by the maple borer (Phenacoccus aceris); the pest vector for LChV-1 is unknown • Reliable detection of the virus is only possible by molecular methods (RT-PCR) • PROTECTION: o PREVENTIVE MEASURES: Healthy plant material, monitoring of maple borer upon confirmation of LChV-2 infections o DIRECT MEASURES: Destroy all infested trees, direct control of the vector (maple borer) • Avoid growing of LChV sensitive varieties such as Lambert, Lapins, Sam, Van, Celeste, Sweetheart, and Bing (fully resistant varieties are not known

Strategy to control Peach Leaf Curl damage (BIOFRUITNET Practice Abstract)

Growing varieties tolerant to leaf peach curl disease lowers copper usage and improves fruit growing and economic return. Practical recommendations and information • HOST PLANTS: peaches and nectarines • SYMPTOMS: o On leaves: symptoms appear about two weeks after leaves emerge from buds, deformations, blisters, thickened curling leaves, and white, yellow to red leave discolorations (Pictures 1 and 2); affected leaves may dry up and fall off o On fruits: Blistered fruit tissue, later wrinkling • DAMAGE: o Infections on fruits make the surface corky and cracked, and affected fruits fall off o When trees are severely affected, the disease can strongly reduce yield and fruit quality o If significant premature leaf drop occurs, trees will be susceptible to drought stress and winter injury • DISEASE TRANSMISSION: o The fungus overwinters in bark and bud scales o The infection of buds happens in early spring during bud swelling (Picture 3) o When temperatures reach above 10°C, infections are possible as early as January o Humid weather promotes the growth and spread of the disease o Additional spores form on the surface of diseased tissue, and these spores cause new infections if the weather remains mild and wet • PROTECTION: o PREVENTIVE MEASURES: Thin out and remove infested shoots by mid-May, thin fruit if the crop load is heavy, and apply copper in the fall after leaf drop o DIRECT MEASURES: From bud swell to bud break during humid weather and temperatures above 10-12°C treat with copper; in case of persistent humid weather, repeat the treatment 1-2 weeks later • Check records of growing degree hours +7°C (sums of active temperatures about 7°C; SAT+7) from the beginning of the year (from January 1st) at meteo-stations in or near your orchards • The first movements of the bud scales are visible when the SAT+7 reaches the value of 800 • Ordinarily, the first treatment by copper is recommended at the value of 1100-1200 SAT+7, but it is advisable to start mostly already at the value of 1000 SAT+7 (in central Europe) • Grow tolerant varieties to leaf peach curl disease, however fully resistant varieties do not exist • Varieties described as the most tolerant: Bella di Roma, Catherine Sel.1, Golden Jubilee, Redhaven, Hardired, Filip, Frumoasa litoralului, Stark Saturn, Creola.; Peach varieties: Bénédicte, Belle de Montélimar and Reine des Vergers are traditional in France • Nowadays, the offer of peach varieties is large, but the lack of reliable data concerning their suitability to organic systems makes the choice difficul