scholarly journals Raw Secondary Metabolites of Trichoderma harzianum T10 in Tapioca Flour Towards Cucumber Damping-off

2020 ◽  
Vol 12 (2) ◽  
pp. 226-234
Author(s):  
Loekas Soesanto ◽  
Hidayatul Ilahiyyah ◽  
Endang Mugiastuti ◽  
Abdul Manan ◽  
Rostaman Rostaman
Keyword(s):  
Secondary Metabolites ◽  
Incubation Period ◽  
Trichoderma Harzianum ◽  
Disease Incidence ◽  
Growth Potential ◽  
Damping Off ◽  
In Planta ◽  
Potato Dextrose Broth ◽  
Tapioca Flour

Trichoderma harzianum is effective for controlling soil-borne pathogenic fungi and producing secondary metabolites. When applied in the field, the raw secondary metabolites are quickly decreased directly by sunlight. One strategy to avoid degradation is the use of tapioca fluor liquid formula for biological control agents. This research aimed to obtain the most effective concentration of tapioca flour in development of raw secondary metabolites of Trichoderma harzianum T10, its effect on damping-off and growth of cucumber. This research was carried out at the screen house and the Plant Protection Laboratory, Faculty of Agriculture, Jenderal Soedirman University from September 2017 up to January 2018. The study was conducted in two stages, i.e., in vitro and in planta. The in vitro stage used completely randomized design with five repetitions and five treatments consisted of T. harzianum T10 in Potato Dextrose Broth, and in 0.5; 1; 1.5; and 2% of tapioca flour media. In in planta, randomized block design was used with five repetitions and six treatments consisted of control, T. harzianum T10 in PDB, and in 0.5; 1; 1.5, and 2% of tapioca flour media. Variables observed were density of conidia, disease incubation period, disease incidence, AUDPC, maximum growth potential, germination ability, plant height, canopy fresh weight, root length, and fresh root weight. Result of the research showed that the highest conidial density (1.23 x 107 conidia mL-1) of T. harzianum T10 was found in 2% tapioca flour with an increase of 63.28% compared to the PDB. The tapioca flour of 1 and 2%, and PDB could suppress the disease incidence by 81.82%. The lowest AUDPC was at 2% tapioca flour. The raw secondary metabolites could not delay the incubation period significantly and increase cucumber plant growth. The novelty is the use of antagonistic fungi in terms of raw secondary metabolites and the discovery of tapioca flour with the right concentration to produce high conidia density and high raw secondary metabolites. The benefits are to find other cheaper ingredients in promoting antagonistic fungal growth and the use of antagonistic fungal bioactive compounds to control plant pathogen

scholarly journals The Effect of Various pH Medium on the Secondary Metabollites Production from Trichoderma harzianum T10 to Control Damping Off on Cucumber Seedlings

2020 ◽  
Vol 3 (2) ◽  
pp. 65
Author(s):  
Nur Chalimah ◽  
Loekas Soesanto ◽  
Woro Sri Suharti
Keyword(s):  
Secondary Metabolites ◽  
Trichoderma Harzianum ◽  
Disease Incidence ◽  
In Vitro Assay ◽  
Cucumber Seedling ◽  
Damping Off ◽  
In Planta ◽  
Vitro Assay ◽  
Cucumber Seedlings

Damping-off is one of the main diseases in cucumber seedlings caused by Pythium sp. Secondary metabolites of Trichoderma harzianum T10 can conduct the control of the disease. The pH of the medium influences the production of secondary metabolites. The research aimed to determine the effective pH medium on production of T. harzianum T10 secondary metabolites, and the effect of the T. harzianum T10 secondary metabolites application in damping-off disease control also to the growth of cucumber seedling. The research was consist of two steps; 1) in vitro assay with various pH levels 5; 3; 3.5; 4; 4.5; 5.5; 6; 6.5; and 7, 2) In planta treatments consisted of control, fungicide (Mancozeb), secondary metabolites in pH 5 and 5.5 with the concentration of 5, 10 and 15% each. The research showed that: 1) the effective pH medium for the production of T. harzianum T10 secondary metabolites was 5 and 5.5. 2) application of the T. harzianum T10 secondary metabolites on pH 5 and 5.5 with a concentration of 5, 10, and 15% could decrease the disease incidence and support cucumber seedling growth.

scholarly journals PENGGUNAAN FORMULA CAIR Trichoderma harzianum T10 BERBAHAN TEPUNG JAGUNG TERHADAP REBAH SEMAI (Pythium sp.) BIBIT MENTIMUN

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Wiwit Ningtias ◽  
Endang Mugiastuti ◽  
Ruth Feti Rahayuniati ◽  
Loekas Soesanto
Keyword(s):  
Trichoderma Harzianum ◽  
In Planta ◽  
Potato Dextrose Broth ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve

Penelitian bertujuan untuk: 1) mengetahui konsentrasi tepung jagung yang tepat untuk medium cair Trichoderma harzianum T10, 2) mengetahui pengaruh aplikasi T. harzianum T10 dalam berbagai konsentrasi medium cair tepung jagung terhadap penekanan penyakit rebah semai dan pertumbuhan bibit mentimun. Penelitian dilaksanakan di Laboratorium Perlindungan Tanaman dan di lahan Fakultas Pertanian, Universitas Jenderal Soedirman pada bulan September 2017 sampai Januari 2018. Pengujian in vitro menggunakan Rancangan Acak Lengkap dengan  lima perlakuan dan  lima ulangan, meliputi perlakuan formula cair medium Potato Dextrose Broth (PDB), formula cair tepung jagung konsentrasi 5, 10, 15 dan 20 g/L. Pengujian in planta menggunakan Rancangan Acak Kelompok dengan 6 perlakuan dan 5 ulangan, membandingkan kontrol dengan tanaman yang diberi perlakuan T. harzianum T10 pada masing-masing formula cair konsentrasi tepung jagung. Variabel yang diamati meliputi kepadatan konidium, masa inkubasi, kejadian penyakit, area under disease progress curve (AUDPC), potensi tumbuh maksimum, daya kecambah, tinggi tanaman, panjang akar, bobot segar akar dan bobot segar tajuk. Hasil penelitian menunjukkan bahwa kepadatan konidium T. harzianum T10 tertinggi pada formula medium cair tepung jagung konsentrasi 20 g/L sebesar 3,67x106 konidium/mL, tetapi belum mampu menyamai medium PDB. Aplikasi T. harzianum T10 yang efektif menekan penyakit rebah semai adalah perlakuan T. harzianum T10 dalam formula cair tepung jagung konsentrasi 15 g/L, yaitu mampu menekan kejadian penyakit 71,43% dan menunda masa inkubasi 35,83%. Aplikasi T. harzianum T10 selain konsentrasi 15 g/L belum berpengaruh terhadap variabel yang diamati dan diukur.

Phaeotheca dimorphospora increases Trichoderma harzianum density in soil and suppresses red pine damping-off caused by Cylindrocladium scoparium

1995 ◽  
Vol 73 (5) ◽  
pp. 693-700 ◽  
Author(s):  
D. Yang ◽  
L. Bernier ◽  
M. Dessureault
Keyword(s):  
Biological Control ◽  
Trichoderma Harzianum ◽  
Plant Pathogens ◽  
Disease Incidence ◽  
Pinus Resinosa ◽  
Red Pine ◽  
Damping Off ◽  
Fungal Antagonist ◽  
Petri Dishes

A fungal antagonist, Phaeotheca dimorphospora, was tested for its ability to control damping-off of red pine (Pinus resinosa) caused by Cylindrocladium scoparium. In vitro, the germination of seeds coated with P. dimorphospora microconidia was significantly increased by 10% compared with uncoated seeds. In experiments carried out in Petri dishes, addition of P. dimorphospora into soil significantly reduced the population of C. scoparium and disease incidence. In the greenhouse, application of P. dimorphospora into the top layer of soil reduced pre- and post-emergence damping-off by 79.5%. Under greenhouse conditions, P. dimorphospora stimulated the population of Trichoderma harzianum, a well-known antagonist of soil-borne plant pathogens. In soil treated with P. dimorphospora, the number of propagules of T. harzianum was 100–500 times higher than in the untreated control, whereas the population of C. scoparium decreased rapidly and was not detectable 1 month after sowing. Key words: Phaeotheca dimorphospora, Trichoderma harzianum, Cylindrocladium scoparium, damping-off, biological control, fungal antagonist, Pinus resinosa.

scholarly journals Application of Trichoderma harzianum T10 Liquid Formula Based On Soybean Flour Against Cucumber Seedlings Damping-Off (Pythium sp.)

Akta Agrosia ◽  
2020 ◽  
Vol 23 (1) ◽  
pp. 11-18
Author(s):  
Lukas Soesanto
Keyword(s):  
Trichoderma Harzianum ◽  
Root Length ◽  
Disease Incidence ◽  
Soybean Flour ◽  
Liquid Formulation ◽  
Damping Off ◽  
Fresh Weight ◽  
Potato Dextrose Broth ◽  
Cucumber Seedlings ◽  
Wet Weight

ABSTRACTProper concentration of soybean flour in the liquid formulation for Trichoderma harzianum T10 growth, its influence to suppress damping-off, and on the growth of cucumber seedlings was investigated. Randomized completely design was used in in vitro test with five treatments and five replicates. The treatments were T. harzianum T10 in Potato Dextrose Broth (control), T. harzianum T10 in soybean fluor of 1, 2, 3 and 4%. Randomiszed block design was used in in planta test with six treatments and five replicates. The treatments consisted of control, T. harzianum T10 in Potato Dextrose Broth, T. harzianum T10 in soybean fluor of 1, 2, 3, and 4%. Variables observed were conidia density, incubation period, disease incidence, area under the disease progress curve, maximum potentially growth, germination persentage, crop height, root fresh weight, shoot fresh weight, and root length. Result of the research showed that the right liquid formulation for T. harzianum T10 growth was the use of soybean fluor with concentration of 2% resulting conidia density as 67,10% compared to PDB. The formulation could suppress the disease incidence, decrease AUDPC value, increase root wet weight, crown wet weight, and root length as 66.67, 66.10, 57.36, 43.81, and 41.81%, respectively, compared to control. Keyword: cucumber, damping-off, liquid formula, soybean flour, Trichoderma harzianum

scholarly journals Uji masa simpan pelet Trichoderma harzianum dan kemampuannya dalam menghambat perkembangan penyakit Layu Fusarium pada bibit tomat.

2018 ◽  
Vol 3 (2) ◽  
pp. 117-127
Author(s):  
Rizka Musfirah ◽  
Rina Sriwati ◽  
Tjut Chamzurni
Keyword(s):  
Vitamin A ◽  
Shelf Life ◽  
Fusarium Oxysporum ◽  
Solanum Lycopersicum ◽  
Plant Height ◽  
Incubation Period ◽  
Fusarium Wilt ◽  
Trichoderma Harzianum ◽  
Wilt Disease ◽  
Damping Off

Abstrak. Tomat (Solanum lycopersicum) merupakan salah satu komoditas pertanian yang ditanam secara luas di seluruh dunia, termasuk di Indonesia, karena memiliki rasa yang khas dan enak, juga memiliki nilai gizi seperti sumber vitamin A dan C yang sangat baik. Produksi tomat mengalami penurunan setiap tahun, salah satunya diakibatkan oleh organisme penganggu tanaman (OPT) yaitu patogen Fusarium oxysporum sehingga perlu dilakukan pengendalian hayati yaitu menggunakan Trichoderma harzianum dalam bentuk formulasi pelet yang praktis, efektif, dan efesien. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) non faktorial yang terdiri dari 6 perlakuan dengan 3 ulangan, setiap perlakuan terdiri dari 10 unit bibit tomat. Penelitian ini terdiri dari 6 perlakuan yaitu perlakuan A (masa simpan pelet T. harzianum  4 minggu), B (masa simpan pelet T. harzianum 3 minggu), C (masa simpan pelet T. harzianum 2 minggu), D (masa simpan pelet T. harzianum 1 minggu), E (masa simpan pelet T. harzianum 0 minggu), F (tanpa perlakuan pelet T. harzianum). Peubah yang diamati yaitu pre-emergence damping off, post-emergence damping off, masa inkubasi, persentase tanaman layu, tinggi tanaman, dan jumlah daun. Hasil penelitian menunjukkan bahwa pelet T. harzianum yang disimpan 4 minggu efektif dalam menghambat perkembangan penyakit layu fusarium seperti menunda masa inkubasi sampai 7 HSI, menekan pre-emergence damping off sampai 90%, post-emergence damping off 92,95%, serta mampu meningkatkan tinggi tanaman sampai 19,63 cm dan meningkatkan jumlah daun rata-rata 7 helai pada 35 HSI. (Storing Period of Trichoderma harzianum Pellets and its ability to Inhibit the development of Fusarium Wilt Disease on Tomato Seeds)Abstract. Tomato (Solanum lycopersicum) is one of the most widely grown commodities in the world, including Indonesia. It has a distinctively good taste and many nutritional value such as vitamin A and C. However, tomato production has decreased every year. One of the main cause is the attacks by pathogens, named Fusarium oxysporum. A Biological control is necessary and the use of Trichoderma harzianum in the form of pellets is recommended because of its effectiveness, efficiency and practical use. This research used a Completely Randomized Design (RAL) non-factorial consisted of 6 treatments with 3 replications, each treatment consisted of 10 units of tomato seedlings. The 6 treatments are named as treatment A (T. harzianum pellet saving 4 weeks), B (T. harzianum pellet saving period 3 weeks), C (shelf life of 2 weeks T. harzianum pellet), D (shelf life of pellet T harzianum 1 week), E (shelf life of pellet T. harzianum 0 weeks), and F (without T. harzianum pellet treatment). The variables observed in this study are pre-emergence damping off, post-emergence damping off, incubation period, the percentage of wilted plants, plant height, and the number of leaves. The results showed that pellets of T. harzianum stored 4 weeks effectively inhibiting the development of fusarium wilt disease such as delaying incubation period up to 7 HSI (Days After Incubation), suppressing the pre-emergence damping off up to 90% and post-emergence damping off to 92.95%, also able to increase the plant height up to 19.63 cm and increase the average leaf number of 7 strands at 35 HSI.

scholarly journals Inhibitory Effect of Trichoderma asperellum Isolate against Ralstonia solanacearum Causing Brinjal Wilt

2021 ◽  
Vol 24 (2) ◽  
pp. 107-120
Author(s):  
SMN Islam ◽  
SS Siddique ◽  
MZH Chowdhury ◽  
NJ Mishu
Keyword(s):  
Ralstonia Solanacearum ◽  
Disease Incidence ◽  
Its Region ◽  
Inhibitory Effect ◽  
Dual Culture ◽  
Trichoderma Asperellum ◽  
In Planta ◽  
Quantitative Test ◽  
Trichoderma Isolate

A native Trichoderma isolate was collected from the agricultural soil of Gazipur. This isolate was identified as a Trichoderma asperellum through morphology and analysis of internal transcribed spacer (ITS) region of ribosomal RNA gene sequence and reconstruction of the phylogenetic tree. The antagonistic effects of the newly identified T. asperellum isolate were assessed against brinjal bacterial wilt caused by Ralstonia solanacearum both in vitro and in planta. Both qualitative and quantitative bioassays were conducted in vitro. For qualitative tests, dual culture and antibacterial activity were carried out, and pathogen growth was observed visually. The antagonism of T. asperellum cell free culture filtrate on the growth of R. solanacearum was conducted in a quantitative test. Successful antagonism was recorded after both in vitro qualitative tests. In addition, the lowest colony forming unit was recorded in 100% of CFC (2.4±0.51 ×103 cfu/ml) in quantitative test. The T. asperellum inoculated plant showed low disease incidence (13.33%) when seedlings were challenged with R. solanacearum in planta experiment. Disease incidence was 100% for seedlings when treated with only R. solanacearum. The results showed that the isolated and identified T. asperellum isolate suppressed R. solanacearum growth in vitro and protected the seedling from wilting in planta. Therefore, this isolate could be considered as a potential isolate. Ann. Bangladesh Agric. (2020) 24(2) : 107-120

scholarly journals MEKANISME PARASITISME TRICHODERMA HARZIANUM TERHADAP FUSARIUM OXYSPORUM PADA SEMAI ACACIA MANGIUM

2015 ◽  
Vol 15 (1) ◽  
pp. 72
Author(s):  
Susanti Tasik ◽  
Siti Muslimah Widyastuti ◽  
Harjono .
Keyword(s):  
Fusarium Oxysporum ◽  
Trichoderma Harzianum ◽  
Acacia Mangium ◽  
Culture Method ◽  
Inhibition Mechanism ◽  
Dual Culture ◽  
In Planta ◽  
Know How ◽  
Soil Borne Fungi

Mechanism of parasitism of Trichoderma harzianum on Fusarium oxysporum on Acacia mangium seedlings. Fusarium oxysporum is one of the most important soil-borne fungi the causal agent of damping-off disease. Detailed information it needed to know how the pathogen can be inhibited by Trichoderma harzianum. The objective of this research was to investigate the inhibition mechanism of T. harzianum on F. oxysporum in vitro and in planta. Green Flourescent Protein (GFP) T. harzianum was used as biocontrol agent of F. oxysporum. An in vitro inhibition test of T. harzianum was performed using dual culture method. In the in planta inhibition tests, seedlings of A. mangium were applied with GFP T. harzianum two days before inoculation of F. oxysporum; GFP T. harzianum was simultaneously applied with F. oxysporum and GFP T. harzianum was applied two days after inoculation of F. oxysporum. The inhibition effect of T. harzianum GFP was observed at seven days incubation, indicated by attachment of T. harzianum to F. oxysporum hyphae. GFP T. harzianum hyphae covered the colonies of F. oxysporum at 12 days after incubation. The highest life percentage of A. mangium seedlings was found on the treatment of GFP T. harzianum two days before inoculation of F. oxysporum (82.22%), whereas the lowest life percentage was found on seedling applied with GFP T. harzianum two days after inoculation of F. oxysporum (64.44%).

scholarly journals EFFECT OF CULTURE CONDITIONS FOR ANTIMICROBIAL ACTIVITY OF MARINE - DERIVED FUNGUS ASPERGILLUS FLOCCULOSUS 01NT.1.1.5

2018 ◽  
Vol 15 (4) ◽  
pp. 721-728
Author(s):  
Phan Thi Hoai Trinh ◽  
Ngo Thi Duy Ngoc ◽  
Vo Thi Dieu Trang ◽  
Phi Quyet Tien ◽  
Bui Minh Ly ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Secondary Metabolites ◽  
Incubation Period ◽  
Marine Fungi ◽  
Antibiotic Production ◽  
Morphological Characteristics ◽  
Colony Growth ◽  
Culture Conditions ◽  
Initial Ph

The biosynthesis of compounds with antibiotic activity produced by marine fungi, strongly depends on their growth conditions. A good understanding of the role of culture conditions in the biosynthesis of metabolites may lead to better exploitation of microbial metabolites. In this study, the influence of culture conditions including incubation period, initial pH and salinity on antimicrobial activity and secondary metabolites production of marine fungus 01NT.1.1.5 was investigated. This isolate, obtained from sponge Stylissa sp. in Nha Trang Bay, exhibited a broad spectrum of in vitro antimicrobial activity to Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Listeria monocytogenes ATCC 19111, Streptococcus faecalis ATCC 19433 and Candida albicans ATCC 10231. According to morphological characteristics and sequence analysis of 28S rDNA, the fungus was identified as Aspergillus flocculosus. The results indicated that antimicrobial activity and metabolite amount were highest when the fungus was cultivated in rice medium with incubation period of 20 days. The optimum salinity of 35 g/L and initial pH of 6.0 were found for the maximum antibiotic production. The colony growth, antimicrobial activity and production of secondary metabolites of the strain A. flocculosus 01NT.1.1.5 varied depending on salt concentrations and initial pH of medium. Particularly, extract of this fungus only showed activity against C. albicans when it was cultured in medium with 30-35 g/L salinity and initial pH 4.0-8.0. The results  indicate that salinity and initial pH along with cultivation period are important factors influencing antimicrobial activity and secondary metabolites of A. flocculosus 01NT.1.1.5, and might be for other marine fungi.

scholarly journals Pengaruh Waktu Inokulasi dan Jumlah Inokulum Terhadap Patogenisitas Phytophthora nicotianae pada Bibit Tembakau

2016 ◽  
Vol 2 (2) ◽  
pp. 75
Author(s):  
Nurul Hidayah ◽  
Titiek Yulianti
Keyword(s):  
Incubation Period ◽  
Disease Incidence ◽  
Inoculum Density ◽  
Phytophthora Nicotianae ◽  
Artificial Inoculation ◽  
Damping Off ◽  
Black Shank ◽  
Plant Variety ◽  
Two Factors ◽  
Screen House

<p>Waktu inokulasi yang tepat serta jumlah inokulum yang digunakan merupakan salah satu faktor yang me-nentukan keberhasilan inokulasi buatan yang lazim dilakukan dalam pengujian ketahanan suatu varietas ter-hadap patogen tertentu. Penelitian ini bertujuan untuk mengetahui waktu inokulasi dan jumlah inokulum Phytophthora nicotianae yang paling efektif untuk dapat menimbulkan gejala penyakit lanas pada bibit tembakau. Penelitian dilaksanakan di laboratorium dan rumah kasa Fitopatologi Balittas, Malang pada bulan Juli Oktober 2006. Metode penelitian menggunakan rancangan acak lengkap (RAL) yang terdiri dari dua faktor, yaitu umur bibit saat inokulasi (faktor I), terdiri dari tiga tingkat yaitu: 1) bibit berumur 5 minggu setelah se-mai (mss), 2) bibit berumur 6 mss dan 3) bibit berumur 7 mss dan jumlah inokulum (faktor II), terdiri dari 4 tingkat yaitu: 1) tanpa inokulum (kontrol), 2) 1.3502.400 zoospora/bibit, 2) 2.7004.800 zoospora/bibit, dan 4) 5.4009.600 zoospora/bibit. Masing-masing kombinasi perlakuan diulang 3 kali. Pengamatan dilaku-kan pada masa inkubasi dan kejadian penyakit. Hasil penelitian menunjukkan bahwa masa inkubasi penyakit dipengaruhi oleh umur bibit saat inokulasi. Bibit yang lebih muda mempunyai masa inkubasi lebih cepat yak-ni 4,5 hari dibandingkan dengan bibit yang lebih tua. Kejadian penyakit tertinggi yaitu sebesar 56,9% terjadi pada saat bibit diinokulasi berumur 5 mss dengan jumlah inokulum 1.3502.400 zoospora/bibit.</p><p> </p><p>Suitable time of inoculation and inoculum density are factors to determine the success of artificial inoculation to evaluate of resistant level of plant variety to pathogen. The aim of this research was to study the appro-priate time of inoculation and inoculum density of Phytophthora nicotianae, the causal agent of black shank and damping off on tobacco seedling. The research was conducted in Phytopathology laboratory and screen house of IToFCRI Malang from July-October 2006. This research was arranged in complete randomized de-sign which consisted two factors and three replicates. The first factor was comprised of three times of ino-culation, and the second was the density of P. nicotianae inoculum. The parameters observed were incuba-tion period and disease incidence. The result showed that the incubation period was affected by the age of seedling when it was inoculated. The younger seedling was more susceptible than the older one. The high disease incidence (56.9%) was reached when the seedling five weeks old and inoculated by inoculum con-tained of 1,3502,400 zoospores/seedling.</p>

Factors affecting the infection of sweet cherry (Prunus avium) fruit by Podosphaera cerasi

Plant Disease ◽  
2021 ◽  
Author(s):  
Claudia Probst ◽  
Binod Pandey ◽  
Prashant Swamy ◽  
Gary Glenn Grove
Keyword(s):  
Powdery Mildew ◽  
Prunus Avium ◽  
Developmental Stages ◽  
Disease Incidence ◽  
The United States ◽  
In Planta ◽  
Full Bloom ◽  
Symptomatic Disease ◽  
Conidial Concentration

Powdery mildew caused by Podosphaera cerasi is the most important fungal disease of sweet cherries in the Pacific Northwest of the United States. In this study, several factors related to disease epidemiology were evaluated. The experiments were conducted to investigate flower susceptibility to P. cerasi infection by in planta and in vitro inoculation. The susceptibility of fruit at various developmental stages was investigated using defined concentrations of P. cerasi conidia. Furthermore, the threshold of conidial concentration required for fruit infection was determined. The pathogen activity during full bloom was limited and not related to fruit disease incidence and severity at harvest. Foliar infections always preceded fruit infections by an average of 42 days during the three years of the study. The onset of fruit infection followed, on average, 66 days after full bloom and appeared simultaneously on all susceptible cherry cultivars in the research orchard. Disease symptoms were only observed on fruit in Biologische Bundesanstalt, Bundessortenamt, and Chemical industry (BBCH) scale 8 (maturity) in all cultivars examined. During this stage, a concentration of 500 conidia/ ml was sufficient to cause fruit infection at harvest. Interaction between the inoculation dates and inoculum conidial concentration revealed a dependency of disease development on the host stage at the time of conidial inoculation; the younger the fruit, the more conidia are needed to cause disease at harvest. Molecular studies showed a rapid increase in conidia viability at the transition from asymptomatic to the symptomatic disease of fruit. No evidence of ontogenic resistance of fruit to powdery mildew infection was observed.

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