Control Effects Of Several Plant Extracts Against Major Diseases Of Apple

Apple is one of the most important fruits in China. With the planted areaexpansion in recent years, apple diseases also continue to occur and aggravate. Valsacanker, ring rot and leaf spot disease are the most common apple diseases, which leadto serious damage. As chemiacal control is the major choice for the control of thediseases, the pollution problem cause much concern in recent years. The safe and lowtoxicity botanical pesticides are in urgent need. In this study, the inhibition effects of39kinds of plant extracts against the three kinds of pathogens, Valsa mali,Botryosphaeria berengeriana, Alternaria alternate were measured. The plant-basedfungicide, F-powder, was developed. The preliminary results are as follows:1. The inhibition effects of39kinds of plant extracts against the three kinds ofpathogens were evaluated by lab test against mycelia growth. For Valsa mali, theplant extracts, Pulsatilla patens, Herba coriandri, Syringa oblata, and Cortexphellodendri, showed most significant inhibition effect, with100%inhibition rates,followed by Radix gentianae and Magnolia officinalis, with99.18%and98.36%inhibition rate respectively. For Botryosphaeria berengeriana, the most notably plantextracts of mycelial growth inhibition was Magnolia officinalis extract, and theinhibition rate was90.93%. The inhibition rates of Cortex mori, Fructus cnidii andSyringa oblata extract were all more than85%. The most notably plant extracts forAlternaria alternate of mycelial growth was Magnolia officinalis, with inhibition rateof81.00%, followed by Syringa oblata, Cortex mori and Portulaca oleracea withinhibition rates over70%.2. Plant extracts showed different inhibitory activity against spore germination ofValsa mali and Alternaria alternate. Magnolia officinalis, Syringa oblate and Herbacoriandri can totally stopped the spore germination of Valsa mali, followed byFructus cnidii, Zanthoxylum bungeanum and Sophora flavescens with inhibition rateover99%. At spore germination tests of Alternaria alternate, the extract of Cortexmori showed the inhibition rate of97.60%. The inhibition rates of Magnolia officinalis, Syringa oblata and Cortex moutan were all above90%.3. F-powder was a mixture of several plant extracts which showed highefficiency against spore germination and mycelial growth of Valsa mali. Theprotecting and therapic effects of F-powder on apple canker were tested by in vitrobranches method. The inhibition rate on lesion extension reached96.96%inprotective experiments, with the equivalent effect to chemical Thiophanate-methyl. Intherapic experiments, the inhibition rate of lesion extension reached93.59%.4. The therapic and eradicate effects of F-powder on apple canker were alsotested by field experiment. In therapic test, the inhibition effect against lesionexpansion was70.21%, better than the chemical thiophanate-methyl. In eradicate test,there was no scar recurrence in the treatment of F-powder. While there were two scarsrecurrence in the treatment of thiophanate-methyl and19scars recurred in the check.It indicated that F-powder could be used as biocontrol agent against Valsa canker onapple.