scholarly journals Sprinkling Irrigation Enhances Production of Oospores of Phytophthora Infestans in Field-Grown Crops of Potato

2000 ◽  
Vol 90 (10) ◽  
pp. 1105-1111 ◽  
Author(s):  
Yigal Cohen ◽  
Sonja Farkash ◽  
Alexander Baider ◽  
David S. Shaw
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Field Experiments ◽  
Soil Surface ◽  
Field Trials ◽  
Detached Leaves ◽  
Oospore Formation ◽  
Potato Crops ◽  
Host Tissues

Two field experiments were conducted to study the effect of overhead sprinkling irrigation on oospore formation by the late blight fungus Phytophthora infestans in potato. Total rain (natural + sprinkling) accumulated in treatments of experiment 1 (winter 1997 to 1998) were 765, 287, and 219 mm and treatments of experiment 2 (winter 1999 to 2000) were 641, 193, and 129 mm. Sporangia from 11 isolates of P. infestans were combined in eight pairs, seven of A1 and A2 and one of A2 and A2 mating type, and were sprayed on field-grown potato crops (42 plants per plot at 7 m2 each) and examined for their ability to form oospores in the host tissues. In experiment 1, oospores were recorded in a total of 132 of 1,680 leaflets (7.9%), 24 of 105 stems, and 2 of 90 tubers. In experiment 2, oospores were recorded in 40 of 519 leaflets (7.7%), but not in any of the 90 stems or the 45 tubers examined. Both the proportion of leaflets containing oospores and the number of oospores per leaflet increased with time after inoculation and were dependent on the rain regime, the position of leaves on the plant, and the isolate pair combination. In both field trials, increasing the rainfall significantly enhanced oospore production in leaves. Leaf samples collected from the soil surface had significantly more oospores than those collected from the midcanopy. Two pairs in experiment 1 were more fertile than the others, whereas the pair used in experiment 2 was the least fertile. The total number of oospores per leaflet usually ranged from 10 to 100 in experiment 1, but only from 2 to 10 in experiment 2. Maximal oospore counts in the field were 200 and 50 in experiments 1 and 2, respectively, but ranged from ≈2,000 to 12,000 oospores per leaflet in detached leaves in the laboratory. We concluded that P. infestans can produce oospores in the foliage of field-grown potato crops, especially when kept wet by regular overhead sprinkling irrigation, but production was far below that in the laboratory.

scholarly journals First Report of Solanum physalifolium as a Host Plant for Phytophthora infestans in Sweden

Plant Disease ◽  
2003 ◽  
Vol 87 (12) ◽  
pp. 1538-1538 ◽  
Author(s):  
B. Andersson ◽  
M. Johansson ◽  
B. Jönsson
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Host Plant ◽  
Mating Type ◽  
Early Summer ◽  
Growing Seasons ◽  
Oospore Formation ◽  
Petri Dishes ◽  
Global Threat ◽  
Shape And Size

In the early summer of 2003, lesions resembling those caused by Phytophthora infestans (Mont.) de Bary on potato were observed on Solanum physalifolium Rusby var. nitidibaccatum (Bitter) Edmonds (2) that was growing as a weed in a parsnip (Pastinaca sativa) field in southern Sweden. When infected leaves of S. physalifolium were observed under the microscope (×200 magnification), sporangia with the same shape and size as those of P. infestans were observed. Pieces of infected leaves of S. physalifolium were put under tuber slices of S. tuberosum (cv. Bintje) in petri dishes and kept at 20°C. After 4 days, mycelium grew through the slices and sporulated profusely. The sporangia on the slices were of the same shape and size as those observed on the infected S. physalifolium leaves. In Sweden, the ratio of A1 and A2 mating types of P. infestans is 50:50, and oospores are commonly found in infected potato crops (1), so isolates from S. physalifolium were tested for mating type by growing them together with reference isolates of a known mating type on agar plates. Nine of the tested isolates were A1 mating type and six were A2 mating type. One self-fertile isolate was found. Naturally infected leaves of S. physalifolium were incubated at 20°C at 100% relative humidity so the lesions could coalesce and to facilitate oospore formation. After 5 days, oospores identical to those of P. infestans were observed under the microscope (×200 magnification). Sporangia produced by isolates originating from S. physalifolium and S. tuberosum were harvested, and a suspension containing 104 sporangia per ml from each isolate was prepared. Five leaves each of S. nigrum, S. physalifolium, and S. tuberosum (cv. Bintje), were inoculated with 10 μl of each sporangial suspension. Inoculated leaves were incubated in sealed petri dishes at 15°C. After 4 days, all S. tuberosum leaves were infected. After 7 days, two of five leaves of S. physalifolium inoculated with the S. tuberosum isolate and two of five S. physalifolium leaves inoculated with the isolate from S. physalifolium were infected. All lesions produced sporangia similar to those formed by P. infestans. S. nigrum was not infected by any of the isolates. The ability of S. physalifolium to act as a host plant for P. infestans producing sporangia during the growing season and oospores for survival between growing seasons may increase the problems of controlling late blight in potato in Sweden. References: (1) J. Dahlberg et al. Field survey of oospore formation by Phytophthora infestans. (Poster Abstr.) Pages 134–135 In: Late Blight: Managing the Global Threat. Proc Global Late Blight Conf. Charlotte Lizarraga, ed. Centro Internacional De La Papa, On-line publication, ISBN 929060-215-5, 2002. (2) J. M. Edmonds. Bot. J. Linn. Soc. 92:1, 1986.

scholarly journals Commercial Fungicide Formulations Induce In Vitro Oospore Formation and Phenotypic Change in Mating Type in Phytophthora infestans

2000 ◽  
Vol 90 (11) ◽  
pp. 1201-1208 ◽  
Author(s):  
Carol Trout Groves ◽  
Jean Beagle Ristaino
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Petri Dish ◽  
Phenotypic Change ◽  
Tomato Production ◽  
Wide Range ◽  
Oospore Formation ◽  
Commercial Fungicide

A wide range of commercially formulated fungicides cause in vitro effects on mating behavior in specific isolates of Phytophthora infestans, the causal agent of late blight of potato and tomato. Four isolates of P. infestans representing each of the four common US genotypes, US-1, US-6, US-7, and US-8 and varying in their sensitivity to metalaxyl, were exposed to a variety of fungicides used to control late blight in petri dish assays at concentrations ranging from 1 to 100 μg a.i./ml. Exposure of each of these normally heterothallic single mating type isolates of P. infestans to 9 of the 11 commercial fungicide formulations tested resulted in the formation of oospores after 2 to 4 weeks. The highest numbers of oospores were formed on media amended with Ridomil 2E (metalaxyl) and Ridomil Gold EC (mefenoxam) at 0.1 to 10 μg a.i./ml, averaging as many as 471 and 450 oospores per petri dish, respectively. Several other fungicides including Maneb, Manzate (Mancozeb), Curzate (cymoxanil + mancozeb), and Acrobat MZ (dimethomorph + mancozeb) also induced oospore formation, producing from 0 to 200 oospores per plate at fungicide concentrations from 0.1 to 10 μg a.i./ml. The metalaxyl resistant isolates formed oospores in response to the fungicides more often than the metalaxyl sensitive isolates. No oospores were formed on media amended with Bravo (chlorothalonil) or Tattoo C (chlorothalonil + propamocarb HCl) and these compounds completely suppressed growth of the isolates at 0.1 and 1 μg a.i./ml. Three metalaxyl resistant A2 isolates mated with both A1 and A2 isolates after exposure to the fungicides Ridomil 2E and Ridomil Gold EC. Alterations in mating type expression were also observed in a metalaxyl sensitive A1 isolate after exposure to Benlate (benomyl). Copious amounts of chemicals are applied annually to potato and tomato production areas to control late blight. Our results indicate that a wide range of chemically diverse fungicides can induce normally heterothallic metalaxyl resistant isolates of P. infestans to form oospores in vitro after short exposures to the fungicides.

scholarly journals Effective control of two genotypes of Phytophthora infestans in the field by three oxathiapiprolin fungicidal mixtures

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258280
Author(s):  
Yigal Cohen ◽  
Avia E. Rubin ◽  
Mariana Galperin
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Field Experiments ◽  
Effective Control ◽  
Disease Development ◽  
Good Efficacy ◽  
Potato Crops ◽  
Effective Sensitivity

In two field experiments, performed in 2020 and 2021, potato Nicola plants were sprayed once with three (Exp. 1) or two (Exp. 2) doses of Zorvec Vinabel (oxathiapiprolin+ zoxamide = ZZ), Zorvec Encantia (oxathiapiprolin+ famoxadone = ZF), Zorvec Endavia (oxathiapiprolin+ benthiavalicarb = ZE), Infinito (= INF) or Mefenoxam (= MFX) and thereafter inoculated with genotype 23A1 or 36A2 of Phytophthora infestans. Disease development was recorded at periodic intervals for a month. In both experiments, Zorvec mixtures were significantly more effective in suppressing the disease than INF or MFX. They delayed the onset of the disease and its progress, regardless the genotype used for inoculation. Among the three Zorvec mixtures, ZZ was least effective and ZE most effective. Sensitivity monitoring assays revealed zero mutants of P. infestans resistant to oxathiapiprolin. The data confirmed good efficacy of Zorvec mixtures, especially ZE, in field-grown potato crops as evident by the very effective control of late blight for one month.

scholarly journals First Report of A1 and A2 Mating Types of Phytophthora infestans on Potato and Tomato in Nepal

Plant Disease ◽  
1998 ◽  
Vol 82 (9) ◽  
pp. 1064-1064 ◽  
Author(s):  
S. K. Shrestha ◽  
K. Shrestha ◽  
K. Kobayashi ◽  
N. Kondo ◽  
R. Nishimura ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Simultaneous Occurrence ◽  
Mating Types ◽  
Isozyme Loci ◽  
Oospore Formation ◽  
The Hill ◽  
Pathogenic Diversity ◽  
Important Disease

Late blight caused by Phytophthora infestans (Mont.) de Bary is an important disease of potato and tomato that occurs annually in the hills and occasionally in the terai (plain) of Nepal. In 1996 and 1997, each year, 50 samples of late blight-infected potato and tomato leaves were collected from the hill and terai areas. The pathogen was cultured on Rye A agar. Each isolate was paired on clear V8 agar with reference isolates DN111 (A1 mating type) and DN107 (A2 mating type) received from Hokkaido University, Japan, and examined for oospore formation after 10 to 15 days of incubation at 20°C. The proportion of A2 isolates was 6% in 1996 and 42% in 1997. The A2 isolates were mainly from the high hills (2,000 to 2,500 m) where local and Andean types of potatoes are grown. Analysis of genotypes of isolates at the glucosephosphate isomerase (GPI-1), malic enzyme (ME), and peptidase (PEP-1) (1,2) isozyme loci revealed genetic diversity between A1 and A2 isolates. A1 isolates from potato were either homozygous (100/100) or heterozygous (86/100) for GPI-1, whereas all A1 isolates from tomato were heterozygous (86/100). All A1 isolates were homozygous (100/100) at the ME locus and heterozygous (92/100) at the PEP-1 locus. A2 isolates were homozygous (100/100) at all isozyme loci. The results show that both A1 and A2 mating types of P. infestans are present in Nepal, and that they display different isozyme genotypes. It is speculated that the A1 type may have migrated with potatoes from Europe while the A2 type may have been introduced with Andean potatoes from Latin America more recently. The simultaneous occurrence of both mating types may allow the fungus to increase its pathogenic diversity and to survive by means of oospores. References: (1) A. A. Mosa et al. Plant Pathol. 42:26, 1993. (2) P. W. Tooley et al. J. Hered. 76:431, 1985.

scholarly journals Complete mitogenome mapping of potato late blight pathogen, Phytophthora infestans A2 mating type

2017 ◽  
Vol 2 (1) ◽  
pp. 90-91
Author(s):  
Virupaksh U. Patil ◽  
G. Vanishree ◽  
Debasis Pattanayak ◽  
Sanjeev Sharma ◽  
Vinay Bhardwaj ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Potato Late Blight ◽  
Complete Mitogenome ◽  
Late Blight Pathogen

scholarly journals Virulence of Phytophthora infestans isolates from potato in Spain

2021 ◽  
Vol 57 (No. 4) ◽  
pp. 279-288
Author(s):  
Jose Ignacio Ruiz de Galarreta ◽  
Alba Alvarez-Morezuelas ◽  
Nestor Alor ◽  
Leire Barandalla ◽  
Enrique Ritter
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Late Blight Resistance ◽  
Blight Resistance ◽  
Genetic Changes ◽  
Detached Leaves ◽  
Severity Of The Disease ◽  
Pathogen Populations ◽  
Incompatibility Reactions

The oomycete Phytophthora infestans is responsible for the disease known as late blight in potato and tomato. It is the plant pathogen that has caused the greatest impact on humankind so far and, despite all the studies that have been made, it remains the most important in this crop. In Spain during the last years a greater severity of the disease has been observed in both, potato and tomato, probably due to genetic changes in pathogen populations described recently. The aim of this study was the characterization of the physiological strains of 52 isolates of P. infestans obtained in different potato-growing areas in Spain. For this purpose, inoculations on detached leaves were performed in order to determine compatibility or incompatibility reactions. A total of 17 physiological races were found. The less frequent virulence factors were Avr5 and Avr8. By studying the epidemiology of the pathogen, a specific breeding program for late blight resistance can be implemented.

scholarly journals Field efficacy of mandipropamid for the control of potato late blight

2010 ◽  
Vol 25 (2) ◽  
pp. 157-161
Author(s):  
Emil Rekanovic ◽  
Milos Stepanovic ◽  
Milan Stevic ◽  
Ivana Potocnik ◽  
Biljana Todorovic ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Potato Late Blight ◽  
Field Trials ◽  
High Efficacy ◽  
Highly Effective ◽  
Field Efficacy ◽  
Disease Pressure

The efficacy of mandipropamid (Revus 250 SC) in controlling Phytophthora infestans in potato was evaluated in field trials. The efficacies of Revus 250 SC in comparison with standard fungicides Quadris (azoxystrobin) were tested in several localities in Serbia (Kasarske Livade, Valjevska Kamenica and Opovo) in 2007 and 2008. Both of the tested fungicides exhibited high efficacy in controlling potato late blight. The differencies in the efficacy of Revus 250 SC (96.3- 99.2%) and Quadris (94.1-95.5%) were insignificant. Our experiments showed that the investigated fungicide was highly effective against P. infestans even under high disease pressure.

scholarly journals Oospore Production of Phytophthora infestans in Potato and Tomato Leaves

1997 ◽  
Vol 87 (2) ◽  
pp. 191-196 ◽  
Author(s):  
Y. Cohen ◽  
S. Farkash ◽  
Z. Reshit ◽  
A. Baider
Keyword(s):  
Relative Humidity ◽  
Environmental Factors ◽  
Phytophthora Infestans ◽  
Optimal Conditions ◽  
In Planta ◽  
Fungal Host ◽  
Factors Affecting ◽  
Detached Leaves ◽  
Oospore Formation ◽  
Initial Lesions

Fungal, host, and environmental factors affecting sexual reproduction of Phytophthora infestans in planta were studied. Intact and detached leaves were coinoculated with sporangia of various combinations of A1 and A2 mating-type isolates; leaves were incubated under various conditions, and oospore production was estimated microscopically within whole, clarified leaflets. Some A1 + A2 isolate combinations were more reproductive than others, whereas some potato genotypes better supported oospore formation than others. Tomato usually supported more oospore formation than potato. To induce oospore formation, A1 and A2 sporangia were usually mixed at a 1:1 ratio. Ratios of 1:19 to 19:1, however, also allowed abundant production of oospores. Optimal temperatures for sexual sporulation ranged from 8 to 15°C, but oospores also were produced at 23°C. Oogonia developed 5 to 6 days after sporangial coinoculation, and oospores developed after 8 to 10 days. Light had little effect on oospore formation in both tomato and potato leaves provided that initial lesions were established under photoperiodic conditions. Although A1 and A2 sporangia usually were mixed before inoculation on leaves to obtain oospores, we found that discrete A1 and A2 lesions produced on opposite sides of the midvein of tomato leaves also induced oospore formation in the midvein and adjacent tissues. Oospores also formed when the two halves of the leaves were cut and separated at 3 days after sporangial coinoculation, which corresponded with the appearance of late blight lesions. The continuous supply of moisture to infected leaves was essential to oospore production. No oospores or oogonia formed in severely diseased plants kept at 50 to 80% relative humidity. Such plants did allow some oospore formation when kept continuously wet for 2 weeks in plastic boxes or tents. Detached leaves floated on water supported the highest sexual sporulation. Under optimal conditions of wetness and temperature, as many as 100 oospores per mm2 of tissue were observed.

scholarly journals Characterization of Phytophthora infestans in Wisconsin from 1993 to 1995

Plant Disease ◽  
1998 ◽  
Vol 82 (4) ◽  
pp. 434-436 ◽  
Author(s):  
K. D. Marshall-Farrar ◽  
M. McGrath ◽  
R. V. James ◽  
W. R. Stevenson
Keyword(s):  
Solanum Tuberosum ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Production Problem ◽  
Significant Production ◽  
Allozyme Genotype ◽  
Late Blight Of Potato

Late blight of potato (Solanum tuberosum), caused by Phytophthora infestans, recently reappeared in Wisconsin and was a significant production problem in 1994. P. infestans isolates collected in Wisconsin from 1993 to 1995 were characterized for the following traits: mating type, sensitivity to metalaxyl, and allozyme genotype for Glucose-6-phosphate isomerase (Gpi). Characterization of these isolates revealed that a new, more aggressive population (A2 mating type, metalaxyl resistant, and Gpi genotype 100/111/122) is displacing the old population (A1 mating type, metalaxyl sensitive, and Gpi genotype 86/100) in Wisconsin.

Sign in / Sign up

Export Citation Format

Share Document