Communications in agricultural and applied biological sciences, 2010
Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseb... more Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseberry (Ribes uva-crispa). Environmental friendly and biological control measures are being sought throughout the world. Especially in organic gooseberry growing effective control measures are needed, because powdery mildew infections may result in a total loss of the crop. In organic currant growing the number of adequate control methods is very limited. Sulphur as a fungicide against powdery mildew in e.g. gooseberry or table grape growing is not recommendable due to possible bleaching of berries and scorching of tender shoots. Various bicarbonate salts are suggested as a good option to control powdery mildew. In a field trial the effect of potassium bicarbonate (Armicarb) on the on the control of powdery mildew of gooseberry was evaluated. Four treatments; i.e. two preventive strategies and two curative strategies, were applied. PLants were sprayed until runoff. The percent of infected ...
Bij de gewasbescherming in de fruitteelt streeft men naar een laagspuitvolume. In de fruitteelt w... more Bij de gewasbescherming in de fruitteelt streeft men naar een laagspuitvolume. In de fruitteelt worden daarvoor veelal werveldoppen gebruikt. Spuiten met een venturidop met een grove druppel zal de drift verminderen. Het gebruik van deze doppen is in Nederland relatief onbekend. In dit artikel worden mogelijkheden gegeven voor werken met deze doppen. Afgifte en spuitvolume werden getest
PPO-fruit voert een meerjarig onderzoek uit naar de bestrijding van taksterfte en stamkanker bij ... more PPO-fruit voert een meerjarig onderzoek uit naar de bestrijding van taksterfte en stamkanker bij rode bes, die veroorzaakt wordt door de schimmel Eutypa lata Het onderzoek richt zich op de effectiviteit van middelen en snoeiwondbehandeling
Bij een spuitdemonstratie in houtig kleinfruit bleek dat er maar weinig spuitmachines helemaal go... more Bij een spuitdemonstratie in houtig kleinfruit bleek dat er maar weinig spuitmachines helemaal goed zijn afgesteld. In houtig kleinfruit zijn machines met dwarsstroomspuittechniek in opkomst, deze machines verdelen de spuitvloeistof gelijkmatiger over het gewas dan de standaard axiaal spuitmachines
Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 3... more Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014, and ‘Conference’ is the main pear cultivar that occupies 75% of the total pear production area. In the Netherlands, pears are kept in controlled atmosphere cold storage up to 11 months after harvest. Occasionally, storage rots are observed when storage crates are contaminated with orchard soil. In a storage trial (2012 to 2013), boxes with ‘Conference’ pears were amended with soil particles from the same orchard from which the pears were harvested (four orchards), and stored for 11 months. Boxes without amended soil were included as controls. In contrast to the control boxes, up to 15% of the pears stored in boxes with soil particles showed typical rot symptoms (lesions) of an unknown causal agent. The lesions showed brown and watery circular necrosis, were slightly sunken, and displayed whitish to yellowish mycelia covering the lesions. To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single spore isolates were transferred to fresh PDA plates. These isolates produced fast-growing colonies with white-yellowish mycelium. Conidia were hyaline, cylindrical, 1 to 3 septate, and 15.8 to 26.4 × 5.3 to 7.9 µm. The fungus was morphologically identical to Neonectria candida (syn. N. ramulariae; anamorph Cylindrocarpon obtusiusculum) (Lombard et al. 2015). The identity of a representative isolate (VTN10Bs3) was confirmed by means of multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, USA). Sequences of the ITS region, translation elongation factor 1-alpha (TEF1), and actin (ACT2) loci were amplified, sequenced, and deposited in GenBank under accessions KU588183 (ITS), KU588186 (TEF1), and KU588184 (ACT2). MegaBLAST analysis revealed that our ITS, TEF1, and ACT2 sequences matched with >99 to 100% identity to N. candida isolates in GenBank (KM249079 and JF735314 [ITS], JF735791 and HM054091 [TEF1], and KM231146 [ACT2]). Subsequently, Koch’s postulates were performed on 15 ‘Conference’ pears. Surface sterilized fruits were inoculated with 20 µl of a suspension of 105 conidiospores ml–1 water, prepared from a 15-day-old PDA culture, after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. Symptoms appeared after 7 days on 100% of the fruits while mock-inoculated controls with water remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the original isolate from the infected pears. Moreover, symptoms observed on artificially inoculated ‘Conference’ pear fruit were identical to the decay observed on ‘Conference’ pears that were obtained from the cold storage experiment. The identity of the reisolations was confirmed as N. candida by sequencing. N. candida (syn. N. ramulariae) is known as a globally distributed soilborne fungus (Domsch et al. 2007), but only few studies have identified the fungus as plant pathogen (Hirooka 2012). This is the first report of N. candida causing storage rot of pears. Importantly, we note that the occurrence of storage rots may be enhanced by contamination of storage crates or fruit with orchard soil.
Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseb... more Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseberry (Ribes uva-crispa). Environmental friendly and biological control measures are being sought throughout the world. Especially in organic currant growing effective control measures are needed, because powdery mildew infections may result in a total loss of the crop. In organic currant growing the number of adequate control methods is very limited. Sulphur as a fungicide against powdery mildew in e.g., gooseberry or table grape growing is not recommendable due to possible bleaching of berries and scorching of tender shoots. Various bicarbonate salts are suggested as a good option to control powdery mildew. In a series of experiments the effect of potassium bicarbonate (formulated and unformulated products) on powdery mildew of gooseberry was evaluated. In the trials different strategies were tested; i.e., preventive and curative strategies. The percent of infected berries, shoots and disease severity were assessed. Very high disease incidences were observed in the untreated control. All potassium bicarbonate treatments significantly reduced the powdery mildew severity in leaves and fruits compared to the untreated controls. The preventive strategies were very successful. However, the number of spray applications was high. Frequently, a severe phytotoxicity caused by potassium bicarbonate was observed. Several experiments were performed with different dosages, timing of sprayings and spray intervals. The potential and limitations of potassium bicarbonate used to control powdery mildew in the field are discussed.
De quarantaineziekte bruinrot van aardappel, veroorzaakt door de bacterie Ralstonia (voorheen : P... more De quarantaineziekte bruinrot van aardappel, veroorzaakt door de bacterie Ralstonia (voorheen : Pseudomonas solanacearum) werd in Nederland voor het eerst met zekerheid aangetroffen in 1992. Het betrof een geisoleerd geval in Zuid-Limburg, dat later verbonden bleek te zijn met een eerder opgetreden besmetting in Belgie. Sindsdien is door een grote inspanning van de Plantenziektenkundige Dienst (PD), de Nederlandse Algemene Keuringsdienst (NAK), het bedrijfsleven en het onderzoek (Plant Research International (PRI - voorheen IPO) en Wageningen Universiteit veel bereikt. Dit artikel geeft een overzicht van de aanpak en het onderzoek sinds de uitbraak van bruinrot in 1995 en werpt een blik vooruit naar toekomstige ontwikkelingen
De oogst was groot bij de telers in de serie Van Knop tot oogst. Nu er tijd is voor reflectie tij... more De oogst was groot bij de telers in de serie Van Knop tot oogst. Nu er tijd is voor reflectie tijdens het rondje kankerknippen of wat schilderwerk, leidt dat tot gemengde gevoelens. Niet iedereen is bezig met de afzet, maar het houdt iedereen wel bezig.
Communications in agricultural and applied biological sciences, 2010
Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseb... more Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseberry (Ribes uva-crispa). Environmental friendly and biological control measures are being sought throughout the world. Especially in organic gooseberry growing effective control measures are needed, because powdery mildew infections may result in a total loss of the crop. In organic currant growing the number of adequate control methods is very limited. Sulphur as a fungicide against powdery mildew in e.g. gooseberry or table grape growing is not recommendable due to possible bleaching of berries and scorching of tender shoots. Various bicarbonate salts are suggested as a good option to control powdery mildew. In a field trial the effect of potassium bicarbonate (Armicarb) on the on the control of powdery mildew of gooseberry was evaluated. Four treatments; i.e. two preventive strategies and two curative strategies, were applied. PLants were sprayed until runoff. The percent of infected ...
Bij de gewasbescherming in de fruitteelt streeft men naar een laagspuitvolume. In de fruitteelt w... more Bij de gewasbescherming in de fruitteelt streeft men naar een laagspuitvolume. In de fruitteelt worden daarvoor veelal werveldoppen gebruikt. Spuiten met een venturidop met een grove druppel zal de drift verminderen. Het gebruik van deze doppen is in Nederland relatief onbekend. In dit artikel worden mogelijkheden gegeven voor werken met deze doppen. Afgifte en spuitvolume werden getest
PPO-fruit voert een meerjarig onderzoek uit naar de bestrijding van taksterfte en stamkanker bij ... more PPO-fruit voert een meerjarig onderzoek uit naar de bestrijding van taksterfte en stamkanker bij rode bes, die veroorzaakt wordt door de schimmel Eutypa lata Het onderzoek richt zich op de effectiviteit van middelen en snoeiwondbehandeling
Bij een spuitdemonstratie in houtig kleinfruit bleek dat er maar weinig spuitmachines helemaal go... more Bij een spuitdemonstratie in houtig kleinfruit bleek dat er maar weinig spuitmachines helemaal goed zijn afgesteld. In houtig kleinfruit zijn machines met dwarsstroomspuittechniek in opkomst, deze machines verdelen de spuitvloeistof gelijkmatiger over het gewas dan de standaard axiaal spuitmachines
Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 3... more Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014, and ‘Conference’ is the main pear cultivar that occupies 75% of the total pear production area. In the Netherlands, pears are kept in controlled atmosphere cold storage up to 11 months after harvest. Occasionally, storage rots are observed when storage crates are contaminated with orchard soil. In a storage trial (2012 to 2013), boxes with ‘Conference’ pears were amended with soil particles from the same orchard from which the pears were harvested (four orchards), and stored for 11 months. Boxes without amended soil were included as controls. In contrast to the control boxes, up to 15% of the pears stored in boxes with soil particles showed typical rot symptoms (lesions) of an unknown causal agent. The lesions showed brown and watery circular necrosis, were slightly sunken, and displayed whitish to yellowish mycelia covering the lesions. To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single spore isolates were transferred to fresh PDA plates. These isolates produced fast-growing colonies with white-yellowish mycelium. Conidia were hyaline, cylindrical, 1 to 3 septate, and 15.8 to 26.4 × 5.3 to 7.9 µm. The fungus was morphologically identical to Neonectria candida (syn. N. ramulariae; anamorph Cylindrocarpon obtusiusculum) (Lombard et al. 2015). The identity of a representative isolate (VTN10Bs3) was confirmed by means of multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, USA). Sequences of the ITS region, translation elongation factor 1-alpha (TEF1), and actin (ACT2) loci were amplified, sequenced, and deposited in GenBank under accessions KU588183 (ITS), KU588186 (TEF1), and KU588184 (ACT2). MegaBLAST analysis revealed that our ITS, TEF1, and ACT2 sequences matched with >99 to 100% identity to N. candida isolates in GenBank (KM249079 and JF735314 [ITS], JF735791 and HM054091 [TEF1], and KM231146 [ACT2]). Subsequently, Koch’s postulates were performed on 15 ‘Conference’ pears. Surface sterilized fruits were inoculated with 20 µl of a suspension of 105 conidiospores ml–1 water, prepared from a 15-day-old PDA culture, after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. Symptoms appeared after 7 days on 100% of the fruits while mock-inoculated controls with water remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the original isolate from the infected pears. Moreover, symptoms observed on artificially inoculated ‘Conference’ pear fruit were identical to the decay observed on ‘Conference’ pears that were obtained from the cold storage experiment. The identity of the reisolations was confirmed as N. candida by sequencing. N. candida (syn. N. ramulariae) is known as a globally distributed soilborne fungus (Domsch et al. 2007), but only few studies have identified the fungus as plant pathogen (Hirooka 2012). This is the first report of N. candida causing storage rot of pears. Importantly, we note that the occurrence of storage rots may be enhanced by contamination of storage crates or fruit with orchard soil.
Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseb... more Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseberry (Ribes uva-crispa). Environmental friendly and biological control measures are being sought throughout the world. Especially in organic currant growing effective control measures are needed, because powdery mildew infections may result in a total loss of the crop. In organic currant growing the number of adequate control methods is very limited. Sulphur as a fungicide against powdery mildew in e.g., gooseberry or table grape growing is not recommendable due to possible bleaching of berries and scorching of tender shoots. Various bicarbonate salts are suggested as a good option to control powdery mildew. In a series of experiments the effect of potassium bicarbonate (formulated and unformulated products) on powdery mildew of gooseberry was evaluated. In the trials different strategies were tested; i.e., preventive and curative strategies. The percent of infected berries, shoots and disease severity were assessed. Very high disease incidences were observed in the untreated control. All potassium bicarbonate treatments significantly reduced the powdery mildew severity in leaves and fruits compared to the untreated controls. The preventive strategies were very successful. However, the number of spray applications was high. Frequently, a severe phytotoxicity caused by potassium bicarbonate was observed. Several experiments were performed with different dosages, timing of sprayings and spray intervals. The potential and limitations of potassium bicarbonate used to control powdery mildew in the field are discussed.
De quarantaineziekte bruinrot van aardappel, veroorzaakt door de bacterie Ralstonia (voorheen : P... more De quarantaineziekte bruinrot van aardappel, veroorzaakt door de bacterie Ralstonia (voorheen : Pseudomonas solanacearum) werd in Nederland voor het eerst met zekerheid aangetroffen in 1992. Het betrof een geisoleerd geval in Zuid-Limburg, dat later verbonden bleek te zijn met een eerder opgetreden besmetting in Belgie. Sindsdien is door een grote inspanning van de Plantenziektenkundige Dienst (PD), de Nederlandse Algemene Keuringsdienst (NAK), het bedrijfsleven en het onderzoek (Plant Research International (PRI - voorheen IPO) en Wageningen Universiteit veel bereikt. Dit artikel geeft een overzicht van de aanpak en het onderzoek sinds de uitbraak van bruinrot in 1995 en werpt een blik vooruit naar toekomstige ontwikkelingen
De oogst was groot bij de telers in de serie Van Knop tot oogst. Nu er tijd is voor reflectie tij... more De oogst was groot bij de telers in de serie Van Knop tot oogst. Nu er tijd is voor reflectie tijdens het rondje kankerknippen of wat schilderwerk, leidt dat tot gemengde gevoelens. Niet iedereen is bezig met de afzet, maar het houdt iedereen wel bezig.
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