The effect of foliar fertilizers on the occurrence of apple scab [Venturia inaequalis Cooke Aderh.]

Apple scab caused by Venturia inaequalis is the most serious fungal disease of apple in Poland. The strategy for apple scab control relies mostly on multiple applications of fungicides, usually 8 to 15 times each gr owing season. Because of the reduction in the range of fungicides and the problem with resistance, alternative methods are being searched for to help control this disease. The objective of this work was to study the effect of different foliar fertilizers f rom Intermag Co., commonly used in apple orchards, against apple scab. Experiments were conducted in 2008 and 2009 on apple trees cv. McIntosh, very susceptible to V. inaequalis . In both seasons, which were favourable to apple scab infections, a significan t reduction in the occurrence of the disease was observed after the applications of a mixture of Chelat Cu 12 Forte + Bormax + Chelat Zn 14 Forte, Alkalin KB + Si, and Alkalin PK. These fertilizers reduced disease severity by more than 80% when used at the highest of the tested concentrations (2%), and by 60% when used at lower concentrations. Two products, Alkalin KB + Si used at 2% and a 1.0% copper solution were phytotoxic to both the leaves and fruits. The results obtained showed that some of the common ly used foliar fertilizers can be useful for controlling apple scab because they cause a reduction in disease intensity (by approx. 70%

A New Bacterial Disease on Bluberry (Vaccinium Corymbosum) Caused by Pseudomonas Spp.

In 2011, leaf spot disease was observed on the blueberry (Vaccinium corymbosum) cv. Nelson growing on a commercial field located in Central Poland. The disease symptoms could be seen as russet brown, irregular spots. The diameter of the spots was 0.3-0.5 cm, and the spots often coalesced. From these leaf spots, a fluorescent bacterium was repeatedly isolated in almost pure culture. Polymerase chain reaction (PCR) using primers Ps-for and Ps-rev, specific for Pseudomonas spp. confirmed that they belong to this genus. Based on LOPAT tests [levan production from sucrose (L), presence of oxidase (O), pectolytic activity on potato (P), the presence of arginine dihydrolase (A), hypersensitivity reaction on tobacco (T)], 6 isolates were classified to the LOPAT group Ib - group of Pseudomonas syringae subsp. savastanoi and Pseudomonas delphini, and one isolate to group Ia - P. syringae. All isolates caused a hypersensitivity reaction on tobacco plants, and symptoms similar to those under natural conditions, when young leaves of blueberry cv. Nelson were inoculated. Sequence analysis of 16S rRNA and rpoB genes showed the highest similarity of 6 studied strains to the species P. avellanae. Further taxonomic study is necessary to enable definitive classification of these isolates. It is the first time that a bacterial disease caused by the Pseudomonas spp. was observed in Poland

A threat to the environment and horticultural plants posed by new Phytophthora species isolated from water

Celem badań było wykrywanie Phytophthora spp. w wodzie w rejonach sadowniczych oraz ocena chorobotwórczości wybranych izolatów dla roślin. Do izolacji gatunków Phytophthora z wody użyto liści pułapkowych różanecznika 'Nova Zembla'. Przynależność gatunkową określano na podstawie cech morfologicznych oraz stosując metody molekularne. W rzekach i stawach stwierdzono 4 gatunki Phytophthora, z dominacją P. lacustris. Występował on we wszystkich analizowanych źródłach wody, niezależnie od terminu detekcji. P. plurivora, jeden z najczęściej występujących gatunków tego rodzaju, wyizolowano z wody i osadów dennych rzeki Jeziorka. Z kolei P. citrophthora stwierdzono w stawach w Kozietułach i Cielądzu, oprócz P. gonapodyides, gatunku uznawanego za saprotrofa. Inokulacja 2 izolatami P. lacustris pędów i korzeni wierzby powodowała rozwój nekrozy (ok. 3 mm) na dobę. Zarówno P. lacustris, jak i P. citrophthora kolonizowały pędy badanych odmian jabłoni i gruszy, ale nekroza rozwijała się ok. 3-krotnie wolniej niż na organach wierzby.Isolation of Phytophthora species from water in orchard areas and pathogenicity of selected isolates toward plants was the purpose of our studies. Four Phytophthora species were isolated from rivers and ponds with P. lacustris being the dominant one. The species was found in all analysed water bodies irrespective of the detection period. P. plurivora known as the most frequent species was found only in the Jeziorka River. P. citrophthora was found in ponds near Kozietuły and Cielądz together with P. gonapodyides, known as a saprotrophic species. Inoculation of stems and roots of Salix spp. with two isolates of P. lacustris resulted in the development of necrosis which spread at a rate of about 3 mm/24 hrs. Both P. lacustris and P. citrophthora colonised shoots of analysed cultivars of apple and pear trees but necrosis spread about 3 times slower than on willow plants

Water as source of environmental dispersion of Phytophthora species

Celem badań było określenie współzależności między stanem zdrowotnym roślin uprawianych pod osłonami i w szkółkach pojemnikowych, a występowaniem Phytophthora spp. w zbiornikach wodnych, z których pobierana jest woda do podlewania. Badania prowadzono przez cały rok w 4 obiektach pod osłonami i w 6 szkółkach pojemnikowych. Do wykrywania gatunków tego rodzaju użyto liści pułapkowych różanecznika (Rhododendron sp.) 'Nova Zembla'. W zbiornikach wodnych w szklarniach wykryto P. plurivora, P. citrophthora, P. cryptogea, P. tropicalis i P. lacustris, podczas gdy w szkółkach dodatkowo P. cambivora i P. cinnamomi. Mimo występowania P. cactorum, P. capsici i P. nicotianae var. nicotianae na porażonych roślinach, w zbiornikach wodnych nie stwierdzono tych gatunków. W wodzie w szklarniach najczęściej wykrywano P. plurivora, a w szkółkach tenże gatunek oraz P. cinnamomi i P. citrophthora.The aim of this study was to find the relationship between health status of crop plants grown in greenhouses and in nurseries and the presence of Phytophthora spp in water reservoirs used for plant watering. Studies were carried out during a year in 4 greenhouse objects and in 6 nurseries. Trap leaves of Rhododendron sp. 'Nova Zembla' were used to detect the study species. P. plurivora, P. citrophthora, P. cryptogea, P. tropicalis and P. lacustris were found in greenhouse reservoirs, while P. cambivora and P. cinnamomi were additionally noted in nurseries. Despite the occurrence of P. cactorum, P. capsici and P. nicotianae var. nicotianae on infested plants, these species were not found in water reservoirs. P. plurivora was noted most frequently in greenhouse reservoirs and the same species together with P. cinnamomi and P. citrophthora - in nurseries

Water as a source of survival and spread of Phytophthora species

Celem podjętych badań było zaprezentowanie danych związanych z występowaniem Phytophthora spp. w polskich rzekach, określenie najczęściej izolowanych gatunków tego rodzaju oraz ich szkodliwości dla roślin. Obiekt badań stanowiły rzeki Jasień, Pisia i Rawka usytuowane w województwach mazowieckim i łódzkim. Pierwsze dwie rzeki przepływają przez tereny ogrodnicze, trzecia Rawka przez pola uprawne i lasy. Do detekcji Phytophthora z rzek użyto liście pułapkowe różanecznika, które umieszczano w wodzie przez cały rok w odstępach miesięcznych. Miarą liczebności Phytophthora spp. w wodzie była liczba nekrotycznych plam na liściach pułapkowych. Zidentyfikowano również do gatunki izolatów uzyskanych z 3 rzek. Występowanie Phytophthora spp. w rzekach stwierdzano przez cały rok, przy czym najmniej plam na liściach pułapkowych odnotowano w III kwartale. Stwierdzono niewielkie różnice w liczbie plam na liściach pułapkowych w zależności od rzeki. W trzech badanych rzekach wykryto 5 gatunków Phytophthora oraz taxon Salixsoil. Przez cały rok z rzek (poza I kwartałem w Pisi) izolowano P. citricola, który występował najczęściej. Ponadto wykryto P. cactorum, P. cambivora, P. cinnamomi i P. megasperma. Izolaty P. cactorum i P. citricola z wody kolonizowały korzenie, części łodyg i liście brzozy, przy czym nekroza rozwijała się istotnie szybciej na tkankach zainokulowanych P. citricola. W doświadczeniu szklarniowym oba gatunki powodowały zgniliznę korzeni i podstawy pędu, co najmniej 4/5 siewek brzozy w ciągu 4 tygodni uprawy. Izolaty P. citricola, uzyskane z Pisi od marca do października, koloniowały blaszki liściowe różanecznika z istotnie wolniejszym rozwojem nekrotycznych plam, przy ich zainokulowaniu kulturami wyizolowanymi w czerwcu, wrześniu i październiku. Wykazano, że gatunek P. citricola może być wnoszony z wodą do nasadzeń żywotnika w czasie zraszania roślin, powodując zarazę wierzchołków pędów.Occurrence of Phytophthora spp. in Polish rivers and pathogenicity of isolates toward some plants were studied. Rivers Jasieniec, Pisia and Rawka were surveyed during all the year with one month interval. First 2 rivers are situated in horticultural areas in Warsaw and Łódź districts whereas the third one is running through agricultural fields and forests. Rhododendron leaves were used as the baits for detection of Phytophthora from water. Number of necrotic spots on baiting leaves was a measure of population densities of Phytophthora spp. in rivers. The occurrence of Phytophthora in water was noticed during all year with the lower density in the 3rd quarter of the year. Five Phytophthora species and taxon Salixsoil were identified among isolates recovered from 3 rivers. During all year from 3 surveyed rivers (except from Pisia in the first quarter) P. citricola was recovered as the most often occurring species. Additionally P. cactorum, P. cambivora, P. cinnamomi and P. megasperma were detected from rivers. In laboratory trials water isolates of P. cactorum and P. citricola colonized roots, stem parts and leaves of birch with the significantly faster spread of necroses on plant parts inoculated by P. citricola. In greenhouse trial both species caused root and stem base rot symptoms of birch seedlings within 4 weeks of growth. Isolates of P. citricola recovered from river from March to October colonized rhododendron leaf blades with significantly slower spread of necroses on tissues inoculated with cultures detected from water in June, September and October. It was shown that P. citricola may be bring to thuja nursery with water used for plant sprinkling and is the causal agent of tip blight

Trichoderma harzianum vietinių izoliatų tinkamumas kontroliuoti braškių verticiliozę

In this research, the antagonistic potential of native Trichoderma harzianum isolates toward important strawberry pathogen Verticllium dahliae was studied. For this purpose, fungi were isolated from the rhizosphere and soil from five different strawberry production sites in Estonia over two growing seasons and were investigated under laboratory and greenhouse conditions. T. harzianum colonies were recovered using a selective medium after 12 days and confirmed through species-specific primers. In the laboratory, although all isolates of Trichoderma produced volatile and non-volatile metabolites, seven isolates which had the strongest inhibitory effects on mycelial growth of pathogen were selected for greenhouse assays. In the greenhouse, the disease severity was measured in a split plot treatment design with seven antagonist isolates applied to the two main treatment factors (soil and root), in which all levels of each factor were used in combination with all other factor levels. The result of greenhouse experiments showed that there was no significant difference among T. harzianum treatments but, among selected T. harzianum isolates, TU79 was the most effective isolate for inhibiting the effects of strawberry Verticillium wilt. In the cross-interaction between the antagonist isolates and their treatments, the minimum disease severity was significantly recorded when both soil and roots were treated with TU79 isolate. However, there was no statistically significant difference when this isolate was applied to the soil alone. The results of this study demonstrated that native T. harzianum isolates collected from Estonian fields have potential biocontrol ability so that they may be extensively used to control Verticillium wilt in strawberry nurseries. © 2016, Lithuanian Institute of Agriculture. All rights reserved.Peer reviewe