Dry rot of potato Fusarium caeruleum (Lib.) Sacc.; effect of planting infected and contaminated sets on plant establishment

The effect on plant establishment of planting infected and contaminated sets of susceptible varieties has been studied in field trials from 1942 to 1945.
Healthy whole sets, and whole sets inoculated internally 3 days before planting, yielded good stands, whilst whole sets with obvious dry-rot lesions present at planting time produced gappy crops.
Healthy cut sets gave satisfactory stands except in one test with Doon Star, whilst sets cut with a contaminated knife at planting time yielded only a few misses in 1943 but many in the unfavourable 1944 season and in 1945.     

Dry rot of potato [Fusarium caeruleum (Lib.) Sacc.]. Investigation on the sources and time of infection

Inoculation with soil samples proved that the fungus causing dry rot is frequently present in field soils in Cheshire and in soil adhering to imported seed tubers. The fungus was viable in soils having a wide range of p H values and in fields which had not grown potatoes for 5-6 years. Other sources of infection include lofts, used sacks, seed boxes, diseased tubers, and knives used for cutting seed potatoes.
Bruised tubers stored in heavily contaminated boxes developed much dry rot; far less disease occurred in unbruised tubers. In boxes containing own-saved seed, healthy tubers in contact with diseased ones remained sound. Bruised tubers in contact with, or contaminated by, diseased tubers contracted dry rot. Cutting seed with a contaminated knife increased the disease seven-fold.
Inoculation of tubers attached to the parent plant showed that little or no infection occurred before lifting. In field trials severe dry rot developed in several varieties 6-8 weeks after lifting.
The results are discussed in relation to seed treatment.     

A Cell Wall-degrading {alpha}-1,3-arabinofuranosidase Produced by the Potato Dry Rot Pathogen Fusarium caeruleum (Lib.) Sacc.

Fusarium caeruleum produced an arabanase which showed maximalactivity at pH 3·5 and which liberated arabinose andits oligomers from -l,3-arabinofuranan and isolated potato tuberparenchyma cell walls. This enzyme was most active in dry rotlesions produced in susceptible potato tubers by a fast-growingisolate of F. caeruleum. This arabanase is not of primary importancein causing tissue maceration, protoplast death or electrolyteloss but it may play a secondary role in these processes.     

Effects of delaying fungicide treatment of wounded potatoes on the incidence of Fusarium dry rot in store

Potato tubers artificially inoculated with Fusarium solani var. coeruleum or F. sulphureum 3 months after harvest were uniformly wounded and held at 5, 10 or 15°C for up to 21 days before immersion in fungicide suspensions. Holding tubers for 14 days at 15°C (curing conditions) or at 5°C did not alter the incidence of dry rot subsequently developing on tubers stored at 10°C, and holding tubers for up to 21 days at 15°C slightly increased disease caused by both pathogens. Thiabendazole, imazalil and prochloraz applied to tubers immediately after wounding almost completely prevented dry rot. Treatment after 3 days was less effective and the amount of disease increased with further delay; fungicides were more effective on tubers held at 5°C than at 10 or 15°C before treatment and storage, and efficacy of the fungicide was decreased by increasing the amount of inoculum on tubers. Wounds became less susceptible to infection by F. solani var. coeruleum and F. sulphureum when tubers were held at 15°C before inoculation, and the incidence of rots was decreased by 70–80% by delaying inoculation for 7 days. Treating tubers with dichlorophen immediately after wounding slightly increased the disease. The effects of fungicide treatment, curing conditions and wound healing are discussed.     

The effects of length of the growth period and of nutrition upon potato-tuber susceptibility to dry rot (Fusarium caeruleum)

Standardized inoculations of the potato varieties Catriona and Doon Star over 6 years have shown that shortening the growth period, either by deferring planting or by removing the haulm prematurely, may considerably reduce susceptibility of the tubers to dry rot (Fusarium caeruleum). Although these treatments reduce dry-matter content of the tubers, no direct relationship between this factor and susceptibility was established. High pre-maturity susceptibility was confirmed at the time of flowering; as the haulm matured susceptibility decreased: when the haulm was dead tubers were resistant. Within a fortnight after any time of premature haulm removal, tubers became completely resistant and showed a decrease in sucrose content but not in content of reducing sugars. It is suggested that susceptibility in the immature tuber is closely related to the content of sucrose, which accumulates because of rapid translocation from the vigorously growing haulm. After harvest, tuber susceptibility slowly increased during storage, with an increase mainly in reducing sugars, but these two factors were not directly related. An application of 6 cwt/acre (753 kg/ha) of 12:12:18 NPK fertilizer to Catriona significantly reduced liability to infection. Additional nitrogen (6 cwt/acre ammonium sulphate) raised tuber susceptibility to that in a non-fertilized plot: when sulphate of ammonia was the only treatment given, the tubers were significantly more susceptible than those receiving complete fertilizer.     

The incidence of stalk rot (Fusarium spp.) on maize hybrids and its effect on yield of maize in Britain

Stalk rot was present in each of 78 maize crops and six hybrid maize trials examined between 1971 and 1975. Fusarium culmorum was the main cause of the disease and was isolated from 67 of the 82 samples from which isolates were made. Lodging was found to be related to, and a natural succession of, the earlier wilting symptom caused by infection with F. culmorum. Yield losses were estimated in 39 crops between 1973 and 1975 and the disease caused a mean reduction of 18-7% in cob weight and 11-2% in 1000-grain weight of infected plants over the 3 yr of the survey.     

The effect on gangrene incidence of dusting seed potatoes with benomyl at time of planting

In 1 out of 2 years' field trials benomyl applied as a dust treatment at time of planting seed potatoes resulted in an increase in potato gangrene in the progeny of both gangrene-free tubers planted in land contaminated with Phoma exigua var. foveata and gangrene-diseased tubers planted in clean land. Gangrene-infected seed tubers treated with benomyl also produced more stems infected with var. foveata than untreated tubers. Two hypotheses are presented to account for this increase in gangrene which does not occur in seed potatoes treated shortly after lifting. In all cultivars tested an organo-mercury dip-treatment increased total numbers of tubers in the seed and chat-size grades without increasing total weight whereas benomyl dust increased the numbers in these grades in Majestic only. The treatment of gangrene-diseased seed with benomyl dust affected neither total weight nor total number of tubers.     

seed rot and root rot complex of beans (Phaseolus vulgaris L.)

Fusarium solani (76%),Phyllosticta phaseolina (12%) andAspergillus flavus (10%) were isolated from bean(Phaseolus vulgaris) seeds showing lesions. Out of these the first two caused 30 per cent and 20 per cent seed rotting respectively after artificial seed inoculations. When inoculum was added into the soil before sowing the seed, 35 per cent and 10 per cent pre-emergence rot ocurred and there was 35 per cent and 15 per cent post-emergence blight when soil with healthy seedlings was inoculated withF. solani andP. phaseolina respectively.F. solani caused similar lesions on bean seeds when inoculated after an injury.F. oxysporum was isolated from the roots of dried bean plants showing necrosis.     

Metabolic activities of the sugarbeet pathogens Fusarium solani (Mart.) Sacc. and Sclerotium rolfsii Sacc. under pyramin stress

Effects of different concentrations of active ingredient of the herbicide pyramin on metabolic activities of Fusarium solani and Sclerotium rolfsii were examined. High concentrations of this herbicide (1000 and 2000 g mL^-1 for F. solani and 100 and 200 g mL^-1 for S. rolfsii) had inhibitory effects on the metabolic activities of both fungi. These were demonstrated by significant decreases in growth, and increases in rates of CO₂ evolved, O₂ consumed and keto acids produced. These were accompanied by increased rates of sugar, nitrate and inorganic phosphorus absorption as well as lowered rates of synthesis of carbohydrates and insoluble nitrogenous (including protein) and phosphorus (including RNA-P and DNA-P) compounds. In addition, rates of excretion of both nitrogen and phosphorus fractions by the mycelial mats were increased.A concentration of 25 g mL^-1 exerted little or no effect on the metabolic activities of these fungi, although S. rolfsii was somewhat sensitive to this concentration.     

Evaluation of biological seed treatments in combination with management practices for the control of Fusarium dry rot of potato

Seed-borne diseases of potato represent a significant constraint to potato production in the US. The use of an effective fungicide in combination with good management practices during cutting and storage, prior to planting, is essential to reducing disease. The efficacy of two biocontrol agents (Bacillus subtilis and Trichoderma harzianum), and a commercially formulated mixture of the chemicals fludioxonil plus mancozeb, applied as seed treatments in combination with different management practices, were evaluated over two years for the control of seed piece decay and sprout rot caused by Fusarium sambucinum. Treatments were made 10 days prior to planting and at planting, and tubers were re-stored at either 18 °C and 95% RH with forced air ventilation at 5950 l min⁻¹ (optimal conditions), at 25 °C in the dark without ventilation (sub-optimal), or not stored at all prior to planting. Seed piece and sprout health were evaluated in vitro and agronomic impacts evaluated in field experiments. Results showed that the biological control agents B. subtilis and T. harzianum provided good control of sprout rot and seed piece decay caused by F. sambucinum, when seed was re-stored under optimal conditions or not re-stored at all. Under optimal conditions, treatment with B. subtilis reduced sprout rot and seed piece decay on average by 66% and 84%, respectively. Treatment with T. harzianum reduced sprout rot and seed piece decay on average by 70% and 81%, respectively. Treatment with fludioxonil + mancozeb reduced sprout rot and seed piece decay under both re-storage regimes. Under optimal conditions, disease incidence and severity was reduced on average by 81% and 97%, respectively. Neither biological control agent reduced seed piece decay incidence under either re-storage regime compared to the untreated controls.     

马铃薯干腐病菌硫色镰孢的生物学特性

从碳源、氮源、酸碱度及生长温度等方面对引起马铃薯干腐病的硫色镰孢Fusarium sulphureum的生物学特性进行了研究。结果表明,该病原菌在不同发育阶段对营养和环境条件的要求存在差异。在固体培养基上,菌落生长最佳碳源为葡萄糖、麦芽糖,最佳氮源为蛋白胨,pH8?为最佳;在液体培养基中,菌丝体生长以麦芽糖为最佳碳源,以硝酸钠为最佳氮源,pH6?为最佳;在分生孢子萌发阶段,在以羧甲基纤维素钠、蛋白胨和谷氨酸为碳、氮源的营养液中,分生孢子萌发率最高,最适pH 6–8。该病菌最适生长温度为25℃,分生孢子致死     

The effect of date of haulm destruction and harvest on the development of dry rot caused by Fusarium solani var. coeruleum on potato tubers

Over 3 yr, the development of dry rot, caused by Fusarium solani var. coeruleum, and the efficacy of treating potato tubers with imazalil was examined in relation to the date of haulm destruction and harvest, and the interval between haulm destruction using diquat dibromide and harvest. The effect of these factors on skin set was also assessed. Planting inoculated seed tubers bearing small rots produced more dry rot on the daughter tubers than planting naturally contaminated seed tubers in 1992. The incidence of dry rot was higher on daughter tubers wounded by a standardised method than on those passed over a reciprocating riddle (riddling). The relationship between the two assessment methods was significantly (P<0.05) correlated in 2 out of 3 yr. Overall, the interval between haulm destruction and harvest had less effect on the incidence of dry rot on daughter tubers after riddling than the date of harvest. In 2 out of 3 yr, the incidence of dry rot on riddled tubers was least on those harvested in August and was much greater on September‐harvested tubers. On tubers harvested in October, the pattern was variable, with the incidence declining in 1 yr but increasing in the other. In the third year, the development of dry rot was similar on August‐ and September‐harvested tubers and was least on those harvested in October. Dipping tubers in imazalil gave significant reductions in dry rot although the amount of the reduction was variable and not affected by time of treatment or the amount of fungicide deposited within the range 6.7 to 19.4 mg imazalil kg^?1. Skin set at harvest, as measured by skin strength or the amount of scuff damage, increased the later the tubers were harvested but did not appear to be affected by the interval between haulm destruction and harvest.     

Moniliformin Accumulation and other Effects of Fusarium avenaceum (Fr.) Sacc. on Kernels of Winter Wheat Cultivars

Accumulation of the mycotoxin moniliformin (MON) and other effects on kernels were examined in 13 Polish winter wheat cultivars inoculated with F. avenaceum (Fr.) Sacc. isolate ATCC 64451. Kernels from inoculated ears were divided into three fractions: Fusarium damaged kernels (FDK), kernels with black point symptoms (BPK) and healthy looking kernels (HLK). The average moniliformin content (mg/kg) was highest in chaff (11.69), lower in infested kernels (FDK + BPK) (2.70) and lowest in HLK (1.16). The mean level (mg/kg) of moniliformin in kernels (total sample) ranged from 0.78 in cv. Liwilla to 3.84 in cv. Gama. Moniliformin levels in chaff were correlated ( r = 0.5322) with the average metabolite concentration (mg/kg) in kernels, and ranged from 4.97 in chaff of cv. Roma to 22.9 of cv. Alba. The moniliformin concentration in kernels (total sample) was highly correlated with the level of the metabolite in diseased kernels. This is the first report of the relationship of black point symptoms with F. avenaceum colonization of kernels and moniliformin accumulation.     

Efficacy of antioxidants on incidence of Fusarium root and pod rot diseases in peanut

Several antioxidants namely ascorbic acid, salicylic acid, sodium benzoates, thiouria and catechol were used as seed treatment and foliar spraying to reduce the incidence of root and pod rot diseases of peanut caused by (Fusarium oxysporum, Fusarium solani and Fusarium moniliforme) as well as to determine of phenolic compounds and oxidative enzymes in the treated plants. Each antioxidant was used at different concentrations (2, 4, 6 and 8 mM) against tested pathogenic fungi in vitro. All antioxidants at 8 mM showed the greatest reduction of mycelial growth of the pathogens. In greenhouse experiments, treated seeds (Giza 5 cv.) or foliar spraying of peanut plants after 30 and 60 days from planting date with each antioxidant at 8 mM reduced severity of both diseases. The treated plants with antioxidants increased accumulation of phenolic compounds and activity levels of oxidative enzymes (catalase, peroxidase and polyphenoloxidase) in infected plants compared to healthy plants.

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