Flower Rot Research Articles

Management of strawberry anthracnose by choice of irrigation system, mulching material and host resistance

We studied, by means of field experiments, the combined effects of irrigation system, mulching material and genetic resistance on the incidence of strawberry anthracnose caused by Colletotrichum acutatum. All trials involved artificial inoculation with fruits colonized by the pathogen. One experiment examined the effects of drip irrigation, overhead sprinkler irrigation, and localized low-pressure tape irrigation, and the effects of grass (Brachiaria sp.) and plastic (polyethylene) mulches, in a split plot, randomized complete block design with four replicates. Lower disease incidence, indicating lower pathogen dispersal, was verified with low-pressure tape and drip irrigation. Flower blight and fruit rot incidence in drip-irrigated plots was minimal (ca. 2% of the disease levels in the plots otherwise irrigated). Grass mulch reduced flower blight in the sprinkler system (up to 80%), but had no significant effect when disease levels were already low due to use of other irrigation systems. A second experiment compared the effects of grass mulch, pine (Pinus elliotti) mulch, and plastic mulch with overhead sprinkler irrigation on strawberry cultivars partially resistant (‘Dover’) and susceptible (‘Campinas’) to the disease in a factorial completely randomized design (CRD). Both organic mulches reduced flower blight and diseased fruit incidence by up to 76% compared to the plastic mulch treatment, especially in the early stages of the epidemics. ‘Dover’ had 70% lower incidence of flower blight than ‘Campinas’, and the effects of organic mulches were more pronounced in ‘Campinas’. A third experiment, with all three irrigation systems combined with inoculated and non-inoculated plots, estimated yield effects due to disease and irrigation system. All plots were covered with plastic mulch in a CRD with six treatments. This experiment clearly confirmed the higher flower blight and fruit rot incidences when sprinkler irrigation was used. In inoculated treatments, fruit yield was significantly reduced in tape-irrigated plots, and more so in sprinkler-irrigated plots. In drip-irrigated plots yield was reduced by only 1%. Overall, our results confirm the importance of cultural and genetic factors as valuable means of strawberry anthracnose management. Adoption of localized irrigation systems, the use of organic mulches and choice of a partially resistant cultivar significantly reduced disease levels in field plots. The importance of water splash for C. acutatum dispersal and its dependency on the soil mulch characteristics are the likely causes for the results observed.

First report on the flower-rot of Crossandra infundibuliformis, a commercial flower crop in India

Crossandra infundibuliformis (L.) Nees is an important commercial plant in many cities in India, which is useful for bouquets, garlands, and decorations. The crop is affected by a new flower rot caused by Fusarium pallidoroseum (Cooke) Sacc. Severely infected plants had purplish leaves, decayed flowers and shortened internodes and were colonized by the cottony colonies of the fungus. The fungus was isolated and caused the same symptoms on plants after inoculation.

First Report of Gray Mold in Tomato Caused by Botrytis cinerea in Baja California, Mexico.

San Quintin Valley, a 60-mile-long coastal plain (30°30'N, 116°W) in the Baja California Peninsula, is one of the major fresh tomato (Lycopersicon esculentum Mill.) production areas in Mexico with more than 8,000 ha. During the last 10 years, the valley's tomato production has declined because of gray mold and stem canker diseases. Flower rot, reddish brown margins on the leaves and stems, and fruit with a gray mold were observed on field-grown tomato plants (Roma type cv. Tequila) in the autumn of 2003. Severity ranging from 55 to 60% was observed at harvest. Infected tissues were sampled and disinfested by immersion in 1% NaOCl for 1 min, rinsed in sterile water, and placed on malt extract agar at 22°C. Fungal conidia were then transferred to 2% potato dextrose agar (PDA). The resulting fungal colonies were definitively identified as Botrytis cinerea Pers.:Fr. The colonies of B. cinerea were first hyaline and white and became dark gray after 96 h. Mycelia were septate with dark branched conidiophores. Conidia were unicellular, ellipsoid, and ranged from 5 to 8 × 8 to 14 μm. Profuse black sclerotia developed in 7-day-old cultures. Infection site analyses in diseased flowers at different stages during the bloom were done with scanning electron microscopy. Fungal hyphae were located predominantly on the receptacle areas, whereas conidia were located in the ovaries as described previously (3). The identity of B. cinerea was confirmed by a restriction digest with ApoI of the 413-kb polymerase chain reaction amplification product obtained with BA2f/BA1r primers (1) and random amplified polymorphic DNA banding patterns (2). Pathogenicity tests were done by spray inoculation of 1-ml aqueous conidial suspension (106 CFU/ml) on 20 healthy plants during the blossom stage. An equal number of plants sprayed with sterile water was used as the control. Plants were incubated at 20 ± 2°C for 5 days. The fungus was reisolated from diseased flowers and peduncles after surface disinfestation (2.5% NaOCl) and plating on PDA. No symptoms were observed in the noninoculated controls. To our knowledge, this is the first report of B. cinerea causing gray mold disease on tomato in Baja California.

Choanephora cucurbitarum 에 의한 부용 꽃썩음병

2001년 진주시 도로변 정원에서 Choanephora cucurbitarum에 의한 부용 꽃썩음병이 발생하였다. 병징은 처음 꽃잎부분이 수침상으로 물려지면서 부패하고 급속히 진전되어 썩었다 PDA또는 병반부위에서 균사는 처음 흰색에서 연한 노란색이며 검은색의 포자낭을 형성되고 백색의 균사가 아주 많이 형성되었다. 단포자성포자는 갈색이고 단포로서 방추형, 타원형 또는 난형이며 크기는 12.3~21.6 <TEX>$\times$</TEX>8.3~11.6<TEX>$\mu$</TEX>m였다. 포자낭은 대부분 구형이고 크기는 42.6-114.2<TEX>$\mu$</TEX>m였다. 포자낭포자는 갈색이고 단포로서 방추형 , 타원형 또는 난형이며 크기는 16.3~23.8<TEX>$\times$</TEX>8.2~13.6<TEX>$\mu$</TEX>m였다. 양쪽 글에 3개에서 수개의 부속사를 형성하였다. 접합포자는 구형의 검은색이고 크기는 46.2-78.4<TEX>$\mu$</TEX>m였다. 균사생육 적온은 3<TEX>$0^{\circ}C$</TEX>였다. 이상과 같이 병원균의 균학적 특징과 병원성을 검정한 결과 이 병을 Choanephora cucurbitarum에 의한 부용 꽃썩음병으로 명명할 것을 제안하고자 한다. In July 2001, rotting and shivering flowers of cotton rose (Hibiscus mutabitis) were fecund in the flower beds along the roadsides in Jinju area. The disease first started as water-soaking, dark-green lesions on the petals, and then whole flower was rotted rapidly, Whitish mycelia and monosporous sporangiophore with monosporous sporangiola were formed abundantly on the lesions. Colony appeared as white to pale yellowish brown mycelia on potato dextrose agar medium (PDA). Monosporous sporangiophore was long slender and branched at the apex, each branch bearing a head of sporangiospores. Sporangium was subglobose in shape and was 42.6-114.2<TEX>$\mu$</TEX>m in size. Monosporous sporangiola were elliptic, fusiform or ovoid, and brown in color and 12.3~21.6 <TEX>$\times$</TEX>8.3~11.6<TEX>$\mu$</TEX>m Um in size. Sporangiospores were elliptic, fusiform or ovoid in shape, dark brown or brown in color and 16.3~23.8<TEX>$\times$</TEX>8.2~13.6<TEX>$\mu$</TEX>m in size, and they had three or more appendages at bipolar end. Zygospores were mostly globose, dark black colored and sized was 46.2-78.4<TEX>$\mu$</TEX>min diameter, The fungus grew on PDA between at 15 to 4<TEX>$0^{\circ}C$</TEX>, and the optimum temperature was 3<TEX>$0^{\circ}C$</TEX>. This is the first report on the flower rot of cotton rose caused by C. cucurbitarum in Korea.

Postharvest Control ofBotrytis cinereaon Cut Rose Flowers with Pyrrolnitrin

Pyrrolnitrin, an antibiotic isolated from Pseudomonas cepacia, was tested for postharvest control of Botrytis cinerea infections on cut Sonia and Royalty rose flowers. After pyrrolnitrin was applied as a bud dip, buds were inoculated with conidia of B. cinerea and stored for 7 days at 2 C. Dip treatments of 12-200 mg/L significantly reduced lesion development during storage at 2 C and promoted poststorage fresh weight gain (an index of cut flower quality). No phytotoxicity was observed on leaves or petals at concentrations of pyrrolnitrin up to 200 mg/L. Dip treatment with 100 mg/L reduced lesion development by about 90% compared to inoculated control flowers and prevented poststorage flower rot (.)

POSTHARVEST CONTROL OF BOTRYTIS CINEREA INFECTIONS ON CUT ROSE FLOWERS WITH PYRROLNITRIN.

Pyrrolnitrin, an antibiotic isolated from Pseudomonas cepacia, was used for postharvest control of B. cinerea infections on cut `Sonia' and `Royalty' rose flowers. Pyrrolnitrin was applied as a bud dip and followed by inoculation with B. cinerea conidia. Dip treatments of 12 to 200 mg·liter-1 pyrrolnitrin significantly reduced disease severity during storage at 2C and promoted post-storage fresh weight gain (an index of cut flower quality). No phytoxicity was observed on leaves or petals at concentrations of up to 200 mg/liter. Dip treatment with 100 mg/liter pyrrolnitrin reduced disease severity to &lt;10% of that on control flowers and prevented post-storage flower rot. This level of disease control was comparable to that achieved with 1800 mg/liter vinclozolin.

Prodiplosis longifila (Diptera: Cecidomyiidae) a New Pest of Citrus in Florida

In the fall of 1984 excessive flower drop was observed in lime Citrus aurantifolia (Christm.) Swingle trees in the vicinity of Homestead, Dade Co., Florida. In a preliminary survey, two lime groves were sampled on the 13th and 25th of October 1984. Sampling consisted of randomly selected collections of floral clusters from 20 trees on each date. Prodiplosis longifila (Gagne) larvae were collected for the first time from lime flowers. Larvae were observed feeding on the style, ovary and filaments. After larval injury, the flowers bore symptoms of fungal infection characterized by necrosis of the ovary and calyx. P. longifila has been reported feeding on wild cotton Gossypium hirsutum L. in Florida (Rainwater 1934) as Cantarinia gossypii (Felt), and is also known to attack alfalfa Medicago sativa L., beans Phaseolus vulgaris L., tomatoes Lycopersicon esculentum L. and potatoes Solanum tuberosum L. in Peru (Gagne 1986). A survey of arthropods associated with lime flowers was conducted on March 20 and March 27, 1985 to establish whether a relationship exists between P. longifila infestation and flower damage. Lime flowers were obtained from commercial lime groves in Dade County, Florida. Clusters of flowers were randomly selected, picked, and transported to the laboratory for examination, where the flowers were opened and examined for the presence of arthropods. Eighty-five percent of 270 lime flowers analyzed contained P. longifila larvae (Chisquare: X2 o5[4] = 9.48) and 11% contained Polyphagotarsonemus latus Banks (Acarina:Tarsonemidae). Species of Hymenoptera were present in 2% of the flowers and Homoptera and Thysanoptera were present in 1% of the flowers. C. sinensis (L) Osb., C. aurantifolia, C. limon (L.)., C. volkaneriana (Ten. & Pasq.) and C. grandis (L.) were sampled for P. longifila March 20, and March 27, 1985 in the 1.37 ha Citrus germplasm collection of the University of Florida Tropical Research and Education Center. Sampling consisted of randomly selected floral clusters from 2 trees for each Citrus species and date. From 20 inflorescences collected for each Citrus species, more C. aurantifolia (1250%) flowers were infested with P. longifila larvae than were C. sinensis, var. Valencia (7%), C. grandis (0%), and C. volkaneriana (0%). Sixty lime flowers infested with P. longifila larvae were dissected and the stamens, ovary, and petals were separated. The petals, stamens and ovary were dipped in Tween 20R (1 drop/50 cc), rinsed in running water for 20 min, disinfected with 95% ethanol for 5 seconds, aseptically cut and then plated out on pH 5.6 potato dextrose agar (PDA). These plates were examined for evidence of fruiting structures after 10 days. Three different isolates were obtained: Cladosporium herbarum LK. ex Fr. var. citricola Farl., Colletotrichum gloesporoides Penz and Penicillium sp.. Infection of Citrus flowers by all or any one of these fungi can cause premature fruit drop. Feeding by P. longifila causes wounding which may play an important role in fungal infection of blossoms and subsequent development of flower rot. Similar type of disease induction with cotton flowers has been previously correlated with feeding by another Cecidomyiidae, Cantarinia gossipii in South America (Jimenez & Ramirez 1984). Symptoms of Colletotrichum infection on the ovary and stamens, where P. longifila feeding occurs differs from other bloom infections,

Treatment of tulips with gibberellic acid by vacuum infiltration

SummaryInitial attempts to reduce the glasshouse period of tulips by vacuum infiltration with GA3 in 200 ppm (v/v) aqueous Tween 80 resulted in over 90% flower losses because of bulb, shoot or flower rot and floral bud blasting. In subsequent experiments fungicides (benomyl, etridiazole, formaldeyhyde and thiram) were added to the solution, GA3 solutions were tested with and without added surfactants (Tween 80 and Agral 90) and two infiltration techniques were tested using a range of vacuums and durations of treatments. The fungicides and surfactants used increased flower losses; vacuum infiltration itself caused some flower losses compared with untreated bulbs. In most cases these flower losses were reduced when GA3 (150-200 ppm) was added to the solution used for infiltration. For cv Apeldoorn previously cooled at 5°C for 12 weeks, vacuum infiltration with GA3 (150-250 ppm) at 10 torr for 5-15 min reduced the duration of the glasshouse period by 5-7 d, compared to untreated bulbs. GA3 treatments also re...

Gibberella zeae . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Gibberella zeae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Wheat, maize, barley, carnations and other ornamentals; also reported infecting Lycopersicon, Pisum, Trifolium and Solanum DISEASE: Seedling blight, pre-emergence and post-emergence blight, root and foot rot, brown rot, culm decay, head or kernel blight (scab or ear scab) of wheat, maize, barley and other cereals. Leaf and flower rot of carnations and other ornamentals. Also reported infecting species of Lycopersicon, Pisum, Trifolium and Solanum . GEOGRAPHICAL DISTRIBUTION: Worldwide on maize and rice in the tropics. Wheat, oats, barley and rye in temperate regions. TRANSMISSION: By planting infected or infested seeds or by planting in infested soil. Secondary infection occurs widely by water droplets under moist conditions or by ascospore discharge.