Cauliflower Residues Research Articles

Orange Peel and Cauliflower Residues Supplementation Induce Morphological and Physiological Tolerance in Common Bean under Drought Stress

Drought is one of the most harmful abiotic stresses affecting the development and yield of the common bean (Phaseolus vulgaris L.). The current climate change and the resulting increased drought will worsen the negative impact of water stress on the plant. The powder of orange peel and cauliflower waste were added as soil supplementation at rates of 7 and 15 g/pot to pots of Phaseolus vulgaris L. under different drought conditions. The growth and physiological analysis were estimated after flowering period of common bean. In the pots where drought will be applied, irrigation was stopped for 2, 4, 6, 8 and 10 days during the flowering period and irrigation was performed again after water stress application. To measure moisture percentage of pots, first dry pots were weighed and after irrigation, their moisture variation in terms of percent was measured during stress from 2 to 10 days. The highest plant height was obtained from control. Leaf area decreased significantly despite the application of different powder, especially after 4 days of drought conditions. The highest root fresh and dry weight, raw ash were observed under control with the application of 7.5 g orange peel powder. Shoot dry weight decreased as the number of days exposed to drought increased, and the application of 15 g orange peel and cauliflower powder gave the highest results compared to control conditions. The highest dry matter was obtained from the application of 7.5 g and 15 cauliflower powder in the absence of drought. It has been revealed that as the duration of exposure to drought increases, the value decreases and plant powders are effective in increasing this value. Chlorophyll a, chlorophyll b and total chlorophyll values decreased significantly with drought, and the highest value was obtained from control conditions, followed by 15 cauliflower powder applications.

Contribution of cauliflower residues to N nutrition of subsequent lettuce crops grown in rotation in an Italian Alpine environment

Up to 75% of nitrogen (N) taken up during cauliflowers production is allocated to leaves, which are left as crop residues after harvest. The inclusion of cauliflower, cultivated alone or intercropped with legumes, in rotation schemes, is a promising tool to optimize N availability to subsequent crops. This original study assessed, for the first time in South Tyrol, Italy, the effect of removal or soil incorporation of cauliflower and clover residues on the growth and N uptake of subsequent lettuce. In 2015, cauliflower was sole-cropped or intercropped with clover, under different N regimes (N0, N1, N2, N3 = 0, 75, 150, 300 kg N ha−1). Cauliflower and clover residues were either removed or incorporated in the soil in 2016. The effects of the residual fertility left by the N fertilizer, the two cropping systems, and the crop residues were assessed on the yield and N uptake of two subsequent lettuce crops. Isotopic 15N-labeled cauliflower residues were additionally used to quantify the N contribution of cauliflower residues to lettuce growth. During the first lettuce crop, residues incorporation was the only factor increasing lettuce yields (+41%) and N uptake (+58%). The residual effect of N1 and N2 rates increased the lettuce N uptake when clover residues were incorporated. During the second lettuce crop, residues incorporation increased lettuce yields (+26%) and N uptake (+44%). On average, 64% and 35% of the lettuce N amounts, in the first and second cycles, respectively, derived from cauliflower residues, and accounted for 38% of the total N contained in cauliflower residues (214 kg N ha−1). Results from this experiment, uncommon for the examined species, demonstrate that incorporation of cauliflower and clover residues provides an excellent source of N for lettuce. Incorporating residues of the preceding cauliflower crop, alone or intercropped with clover, before establishing the lettuce crop, substantially reduce the N fertilization needs of subsequent lettuce crops.

Emissions of nitrous oxide and ammonia after cauliflower harvest are influenced by soil type and crop residue management

The decomposition of vegetable crop residues, e.g. from Brassica species, can cause substantial nitrous oxide (N2O) and ammonia (NH3) emissions due to their high nutrient and water contents. One promising approach to reduce these harmful emissions is optimizing post-harvest crop residue management. So far published results on the effects of different crop residue placement techniques on N2O and NH3 emissions do not give a consistent picture. One of the key issues is the diverse experimental conditions, in particular with respect to soil characteristics. Therefore, we studied the effects of cauliflower residue management, i.e. no residues (control), surface application (mulch), incorporation by mixing (mix), incorporation by ploughing (plough), on N2O and NH3 emissions in a 7.5-months field study, using a unique open-air facility featuring three different soils with contrasting soil texture (loamy sand, silt loam, sandy clay loam). Cauliflower residues caused the highest N2O emissions after ploughing (2.3–3.4 kg N2O–N ha−1, 1.5–2.2 % of residue-N), irrespective of the soil type. In contrast, ammonia emissions were only affected by the residue placement technique in loamy sand, which exhibited the highest emissions in the mulch treatment (1.9 kg NH3–N ha−1, 1.2 % of residue-N). In conclusion, under the given conditions incorporating crop residues by ploughing appears to produce the highest N2O emissions in a range of soils, whereas surface application may primarily increase NH3 emissions in coarse-textured soils.

Overwintering grass-clover as intercrop and moderately reduced nitrogen fertilization maintain yield and reduce the risk of nitrate leaching in an organic cauliflower (Brassica oleracea L. var. botrytis) agroecosystem

Cauliflower (Brassica oleracea L. var. botrytis) has high nitrogen (N) demand during growing, but due to its low N use efficiency and N-rich residues, it may cause N losses by leaching after harvest. A field experiment was conducted to investigate the effect of overwintering grass-clover as an intercrop and moderately reduced N fertilization on organic cauliflower yield and risk of nitrate leaching. The experiment tested sole-cropped (S) and intercropped (I) systems using a substitution design and two N fertilizer rates (180 and 230kgNha−1). To investigate the competition between cauliflower and grass-clover, cauliflower grown alone with empty grass-clover rows (Semp) and grass-clover grown alone with empty cauliflower rows (GCemp) were included. The results showed that marketable yield was maintained in the I system compared to in the S system when calculated per meter crop row, and when N fertilization was moderately reduced. The Relative Competition Index (RCI) values in the I system were lower than 0, indicating that cauliflower growth was not interfered in the I system. The ability for aboveground N accumulation in the S and I systems was similar, but the N content of cauliflower residues in the S system was 33 and 23kgha−1 higher than in the I system in 2012 and 2013, respectively. The S system had 168kgNinorgha−1 in the soil layer of 0–1.5m at the start of leaching in 2013, which was 40kgNha−1 higher than the I system. Reduced N fertilizer level led to 22kgha−1 lower soil Ninorg at the end of leaching. However, the effect of system and N level on soil residual Ninorg per unit marketable yield was not significantly different. Intercropping cauliflower with overwintering grass-clover and moderately reduced N fertilization was feasible in organic cauliflower production, with regard to maintaining marketable yield and reducing the risk of nitrate leaching in the agroecosystem.

Form and development of nitrogen in plant waste extracts, effects of papain on nitrogen transfer and use of extracts for lettuce fertigation

SummaryLiquid organic fertilisers made from extracts of plant residues can provide a sustainable alternative for vegetable production, since they are not produced using fossil fuels and are easy to apply as side-dressing fertilisers. The aims of this study were: (i) to evaluate the influence of extraction time and the addition of papain on the composition of aqueous extracts of cauliflower, tomato leaf, or whole tomato plant residues; and (ii) to explore the fertigation potential of such extracts for lettuce cultivation. After 10 d of extraction, approx. 30% of all plant residue nitrogen (N) was transferred to the liquid fraction, of which 8 – 15% was in mineral form. Ammonium was the main mineral form of N in all extracts. Nitrate concentrations were higher in whole tomato plant residues than in tomato leaves or cauliflower residues. The addition of papain increased the amount of total N in solution when used at concentrations ≥ 400 mg l–1.Compared to the mineral nutrient solution (control), plant extracts were comparable in mineral N, lower in phosphate, and higher in all other nutrients examined, as well as in Na+ and Cl– ions. The application of each extract to lettuce seedlings resulted in reduced plant growth in all treatments compared to the control, probably due to their higher electrical conductivity and, possibly, ammonium toxicity. Further research is needed in order to balance the nutrient composition and to increase the transfer of plant residue nutrients into the extracts.

N2O fluxes from a Haplic Luvisol under intensive production of lettuce and cauliflower as affected by different N‐fertilization strategies

AbstractVegetable‐production systems often show high soil mineral‐N contents and, thus, are potential sources for the release of the climate‐relevant trace gas N2O from soils. Despite numerous investigations on N2O fluxes, information on the impact of vegetable‐production systems on N2O emissions in regions with winter frost is still rare. This present study aimed at measuring the annual N2O emissions and the total yield of a lettuce–cauliflower rotation at different fertilization rates on a Haplic Luvisol in a region exposed to winter frost (S Germany). We measured N2O emissions from plots fertilized with 0, 319, 401, and 528 kg N ha–1 (where the latter three amounts represented a strongly reduced N‐fertilization strategy, a target value system [TVS] in Germany, and the N amount fertilized under good agricultural practices). The N2O release from the treatments was 2.3, 5.7, 8.8, and 10.6 kg N2O‐N ha–1 y–1, respectively. The corresponding emission factors calculated on the basis of the total N input ranged between 1.3% and 1.6%. Winter emission accounted for 45% of the annual emissions, and a major part occurred after the incorporation of cauliflower residues. The annual N2O emission was positively correlated with the nitrate content of the top soil (0–25 cm) and with the N surpluses of the N balance. Reducing the amount of N fertilizer applied significantly reduced N2O fluxes. Since there was no significant effect on yields if fertilization was reduced from 528 kg N ha–1 according to “good agricultural practice” to 401 kg N ha–1 determined by the TVS, we recommend this optimized fertilization strategy.

Nitrogen mineralization, plant uptake and nitrate leaching following the incorporation of (15N)-labeled cauliflower crop residues (Brassica oleracea) into the soil: a 3-year lysimeter study

A 3-year field lysimeter experiment was performed to determine transformations of 15N-labeled cauliflower (Brassica oleracea) residues incorporated into lysimeter topsoil in a potato (Solanum tuberosum)/cauliflower rotation. Only the potato crop received 150 kg mineral N ha−1y−1. Cauliflower yields were high (12–13 t fresh matter ha−1), and N returned to the soil represented 51% of the aboveground plant N uptake. The 15N recovery by the potato/cauliflower rotation began at 46%, then decreased sharply to 12 and 6% for the second and third year, respectively. The cumulative 15N leaching rate was only 3%; 63% remained in the soil 3 years after incorporation. Soil N mineralization rates described by a parallel first-order kinetic model predicted 27, 7 and 6% of residual N lost annually during the first, second and third year, respectively. Thus, a potato/cauliflower rotation with moderate N fertilization optimizes N recovery of crop residues and can control leaching loss efficiently.

Effect of Cauliflower Residue Amendments and Soil Solarization on Verticillium Wilt Control in Artichoke.

The effect of fresh cauliflower residue amendment alone and with a low dose of metham sodium (MS) combined with soil solarization was investigated for the control of Verticillium wilt of artichoke in two commercial fields under artichoke-cauliflower rotation. Treatments were a factorial combination of three main plots (an unamended control, soil amended with cauliflower residue, and a combination of cauliflower residue and a low dose of MS) and two subplots (application of a plastic cover or uncovered). Inoculum densities of Verticillium dahliae were measured before and after soil treatments as well as disease incidence, symptom severity, and yield. Although soil solarization reduced inoculum of V. dahliae and the incidence of Verticillium wilt of artichoke, no added benefit was obtained when solarization was used with cauliflower residue amendments. In addition to toxic volatile compounds, other mechanisms could be involved in disease suppression because the effects of incorporating cauliflower residue were not enhanced by the plastic covering. The effect of cauliflower residues on populations of V. dahliae microsclerotia in soil was inconsistent, possibly due to varying pretreatment inoculum levels. Treatments with cauliflower residue amendments and low doses of MS maintained low inoculum densities in the fields until the end of the growing season and significantly reduced the percentage of infected plants.

Manipulating Nitrogen Release from Nitrogen‐Rich Crop Residues using Organic Wastes under Field Conditions

Following mineralization of N‐rich crop residues, large amounts of mineral N can be released into the soil. Manipulating N mineralization of crop residues may be an option to reduce NO3− in soil. The potential to manipulate the N release from vegetable crop residues by using organic wastes was tested under field conditions. At the start of the experiment, cauliflower (Brassica oleracea L. var. botrytis L.) residues (∼73 Mg fresh matter ha−1) together with an immobilizer waste (∼5 Mg C ha−1 of straw, green waste compost, sawdust, or paper sludge) were incorporated into a silt loam soil. After 154 d, a remineralizing waste (∼1 Mg C ha−1 of vinasse or dairy sludge) was incorporated. During the field experiment, the mineral N content in the soil was measured at regular time intervals, and net N release, NO3− leaching, and denitrification were simulated using a N mineralization–immobilization model coupled to a NO3− leaching model. Straw, green waste compost, and sawdust were able to immobilize between 54 and 68% of the N released by the cauliflower residues and reduced NO3− leaching by 56 to 68%. Paper sludge released an extra amount of N due to its low C/N ratio. No consistent remineralization of N could be found in any of the treatments, probably due to an unsuitable composition of the remineralizer wastes. Manipulating N release of N‐rich crop residues by using organic wastes may be a suitable method to reduce NO3− leaching; however, stimulating remineralization of immobilized N by the start of the following spring may not be easy to achieve.

Dynamics of aggregate stability and biological binding agents during decomposition of organic materials

SummaryThe relative importance of different binding mechanisms and associated biological binding agents on aggregate stability is still unclear. The aim of this study was to evaluate the role of various aggregate binding agents during the decomposition of cauliflower residues, wheat straw, cattle manure and poultry woody compost. We measured aggregate stability, hot‐water extractable polysaccharide, C mineralization, fungal and microbial biomass dynamics in an amended silt loam soil, under controlled conditions. Soil aggregate stability was measured using three methods involving fast wetting, slow wetting and mechanical breakdown. Aggregate stability to slow wetting followed the same dynamics as C mineralization and was well correlated with polysaccharide content for cauliflower residues and wheat straw. This relationship is in agreement with the hypothesis that the rapid microbially induced improvement in aggregate stability that follows fresh organic residue additions at least partly involves labile polysaccharides. The transient increase in the two other types of stability was not directly related to C mineralization dynamics and seemed to be influenced by fungal hyphal length. Fungi would provide resistance to mechanical breakdown and slaking. The dynamic behaviour of biological binding agents was only partly explained by the initial quality of the organic materials, as characterized by Van Soest proximal fractionation.Dynamique de la stabilité structurale et des facteurs agrégeants biologiques associée à la décomposition de produits organiques.RésuméL’importance relative des différents mécanismes d’agrégation et des facteurs agrégeants biologiques associés n’est toujours pas clairement établie. L’objectif de cette étude est d’évaluer l’effet de différents facteurs agrégeants sur la stabilité structurale au cours de la décomposition de produits organiques: de résidus de chou‐fleur, de paille de blé, d’un fumier de bovin et d’un compost de fientes de volailles et d’écorce de peuplier. Nous avons mesuré les dynamiques de stabilité des agrégats, de minéralisation du C et des biomasses microbienne et fongique d’un sol limoneux amendé pour des conditions contrôlées. La stabilité structurale est mesurée par trois traitements d’intensités différentes correspondant à une humectation rapide, une humectation lente et une désagrégation mécanique sur des agrégats. La stabilité structurale soumise à l’humectation lente suit les mêmes dynamiques que la minéralisation du C et est bien corrélée avec la concentration en polysaccharides pour les résidus de chou‐fleur et la paille de blé. Cette corrélation confirme l’hypothèse que les polysaccharides labiles participent au moins partiellement à l’amélioration rapide de la stabilité des agrégats induite par l’activité microbienne à la suite d’apports de produits organiques frais. L’augmentation transitoire des deux autres types de stabilité structurale n’est pas directement liée aux dynamiques de minéralisation du C et est plutôt influencée par la longueur des hyphes mycéliens. Le rôle des champignons serait alors d’accroître la résistance des agrégats soumis à des forces de désagrégation plus importantes. Le comportement des différents agents agrégeants biologiques n’est que partiellement expliqué par la composition initiale des produits organiques, caractérisés par la méthode de fractionnement Van Soest.

Influence of DCD and DMPP on soil N dynamics after incorporation of vegetable crop residues

We have investigated the effect of two nitrification inhibitors, 3,4-dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD), on the accumulation of \({\text{NH}}^{{\text{ + }}}_{{\text{4}}} {\text{ - N}}\) and \({\text{NO}}^{ - }_{3} - {\text{N}}\) after incorporation of cauliflower residues in incubation experiments. Cauliflower leaves were incubated with soil and DCD or DMPP at two application rates [8.93 and 17.9 mg active component (ac) kg−1 for DCD; 0.89 and 1.79 mg ac kg−1 for DMPP]. Both doses of DCD and DMPP increased \({\text{NH}}^{ + }_{4} - {\text{N}}\) on average by 18.9 and 26.0 mg N kg−1 for DCD1 (during 30 days) and DCD2 (during 45 days), respectively, and on average by 14.4 mg N kg−1 for DMPP1 and DMPP2 during a period of at least 95 days. In DCD-treated soils, \({\text{NO}}^{{\text{ - }}}_{{\text{3}}} {\text{ - N}}\) data followed an S-shaped curve, indicating that nitrification restarted during the experiment: inhibition was on average 24% during 35 days for DCD1 and on average 45% during 49 days for DCD2. Thereafter, \({\text{NO}}^{ - }_{3} - {\text{N}}\) amount in DCD-treated soils exceeded that of the cauliflower-only treatment by 31% for DCD1 and 78% for DCD2, probably due to a nitrogen release from DCD itself and a priming effect induced by DCD. In DMPP-treated soils, \({\text{NO}}^{ - }_{3} - {\text{N}}\) data followed a linear pattern since nitrification was inhibited during the complete incubation (95 days): inhibition was on average 56 and 64% for DMPP1 and DMPP2, respectively. DMPP did not affect the N mineralization of the crop residues. Under favourable conditions, DCD is able to inhibit the nitrification from crop residues for 50 days and DMPP for at least 95 days. Hence, especially DMPP shows a potential to reduce \({\text{NO}}^{ - }_{3} \) leaching after incorporation of crop residues.

THE ENVIRONMENTAL IMPACT OF NITROGEN IN FIELD VEGETABLE PRODUCTION

Many intensive systems of field vegetable production are not sustainable because they lose excessive amounts of nitrogen (N) to the environment. Processes in the N cycle of agricultural systems include assimilation, mineralization/immobilization, nitrification, denitrification, ammonia volatilization, nitrate leaching, runoff and erosion. Emission of N from agriculture may affect the quality of the atmosphere, ground and surface waters. This occurs through leaching, ammonia volatilization, denitrification, nitrification, runoff and erosion. In field vegetable production, nitrate leaching is the dominant process affecting the environment. Often, large amounts of nitrogen, including residual soil mineral nitrogen and the nitrogen present in crop residues remain in the soil after harvest of the crop. Both sources of nitrogen may affect groundwater quality through nitrate leaching. Residual soil mineral nitrogen levels after application of the recommended rates of nitrogen fertiliser to Brussels sprouts, white cabbage and onions are low to moderate (20-75 kg N ha-1). Application of the recommended rates to other field vegetables, however, may leave large amounts of residual soil mineral nitrogen, especially after crops that are harvested before maturing, e.g., spinach, where residual soil mineral nitrogen may even exceed 200 kg N ha-1. Obviously, large amounts of nitrate will then be at risk of leaching and denitrifying in the period after harvest. Crop residues of spinach and celeriac contain 25-60 kg N ha-1, cauliflower residues 80-120 kg N ha-1, and white cabbage and Brussels sprout residues as much as 150-250 kg N ha-1. If the residues decompose before winter, nitrogen from the decomposed plant material may leach or denitrify during the subsequent winter period. Realistic estimates of nitrogen losses through leaching and denitrification after harvest of field vegetables were generated with a simulation model. It was calculated that leaching losses may exceed 200 kg N ha-1 after spinach or leeks, but denitrification was low. Leaching and denitrification losses after Brussels sprouts and cabbage were much lower.

N mineralization and nitrate leaching from vegetable crop residues under field conditions: a model evaluation

Six different vegetable crop residues were incorporated in the field and N mineralization from the residues and from an unamended plot was followed over 4 months by periodically monitoring mineral N contents of the soil. The crop residues were also fractionated according to a modified Stevenson chemical fractionation. Nitrogen mineralization parameters of the first order kinetic model N( t)= N A(1−e − kt ) were derived from the chemical fractionation data. The first order model was used in combination with a model describing the temperature dependence of N mineralization and a simple leaching model to predict N mineralization rates and nitrate redistribution after crop residue incorporation under field conditions. Comparison of predicted and measured mineral N contents in the upper soil layer (0–30 cm) before the start of leaching showed that the model was able to predict N mineralization from both soil organic matter and crop residues under field conditions. From the onset of leaching, mineral N contents were slightly overestimated in the upper layer and underestimated in the lower soil layers. Although the Burns leaching model underestimated the leaching rate, the general pattern of nitrate movement was simulated satisfactorily. Statistical analysis using the variance ratio test yielded small but significant F values, indicating that the model can still be improved. The modelling efficiency was rather high and the coefficient of residual mass very close to zero. Linear regression between measured and simulated nitrate contents over the whole profile (0–120 cm) for all samplings yielded Y=9.6+0.876 X ( r=0.94***) with all deviations smaller than 25 kg N ha −1. Total N mineralization ranged from 48 kg N ha −1 for the control plot to 136 kg N ha −1 for the plots with cauliflower residues and cumulative leaching losses from 26–66 kg N ha −1, with most of the mineral N left in the 60–120 cm layer. These results show that N losses by leaching in winter can be high when vegetable crop residues are incorporated, even when there is little mineral N in the soil at the time of incorporation.

Control by metham-sodium ofxanthomonas campestris pv.Campestris and the pathogen’s survival in soil

Detection and quantitative estimation ofXanthomonas campestris pv.campestris (XCC) from soils were done on Kritzman’s selective medium (KSM). The composition of KSM, its selectivity and the recovery of 64 isolates ofXCC obtained from Israel, Holland, Taiwan, the USA, and Germany are given in detail.XCC was isolated from soil in Israel 22 months after infected cauliflower residues were incorporated into the soil. Metham-sodium (MES) at 16 ml/kg (32.7% active compound) of air-dried soil killed more than 99.9% and 99% ofXCC in soil in laboratory and field tests, respectively. MES applied at this ratevia the irrigation system in a field infested withXCC, significantly reduced counts of the pathogen in stems, siliques and seeds, and the incidence of plants with black rot symptoms. The treatment was more successful in reducing disease incidence when applied to the soil at a depth of 30 or 40 cm rather than 20 cm. It is recommended that a seed treatment be combined with fumigation of soil with MES for the production of seeds free ofXCC.

By-products from the canning industry as feedstuff for ruminants: Digestibility and its prediction from chemical composition and laboratory bioassays

Fresh artichoke by-product, pepper and cauliflower residues, dried tomato pulp and fresh or ensiled apple pomace were fed, together with alfalfa hay, to adult ewes in four diets including 20, 40, 60 and 80% of each by-product, and organic matter digestibility (OMD) was estimated by the regression and difference methods. The OMD of ensiled artichoke and pea haulms was also determined directly giving both by-products as a whole diet. The OMD varied linearly with the dietary level of inclusion of each by-product, except for diets including pepper residues, where digestibility was similar tothat of the alfalfa hay. The digestible organic matter (DOM) content (g kg −1 DM) of fresh artichoke, pea haulms, apple pomace, pepper and cauliflower residues and dried tomato pulp was estimated to be 750, 650, 847, 615, 679 and 449, respectively, and that of ensiled artichoke, pea haulms and apple pomace 669, 508 and 739, respectively. Dry matter disappearances after in vitro incubation with rumen liquor-pepsin or pepsin-cellulase solutions and after 24 as well as 48 h of in situ incubation were determined to study their usefulness as predictors of OMD compared with several chemical parameters. The most accurate predictions were obtained with the in situ method after 48 h of incubation ( r = 0.97; RSD = ± 3.03) followed by the rumen liquor-pepsin procedure ( r = 0.94; RSD = ± 4.62) and pepsin-cellulase bioassay ( r = 0.88; RSD = ± 6.09). Chemical parameters proved to be poor predictors of OMD for this sort of by-product (RSD ranged from ± 7.00 to ± 11.96).

Farm biomass utilization alternatives

Biomass, which is available in plenty, plays an important role in meeting the energy needs of the rural areas in most of the developing countries. Different crop residues were screened for optimum utilization. Cauliflower residues can be used as an unconventional fodder because of their nutritive value, while bhindi and tomato residues can be used for biogas production and mustard residues for charcoal production.

Disease cycle in New Zealand of light leaf spot of brassicas, induced byPyrenopeziza brassicae

Abstract This paper discusses the role of a pothecia of Pyrenopeziza brassicae Sutton & Rawlinson in the disease cycle of light leaf spot of brassicas. Apothecia survived for up to 27 weeks on the soil surface under a weed canopy but for less than 4 weeks when buried in the soil. Apothecia stored for up to 50 weeks on dry cauliflower residues in the laboratory discharged ascospores when wetted. Ascospores discharged on to glass slides remained viable for up to 8 weeks at about 20°C and 70% RH. Less than 1% of conidia incorporated into unsterilised volcanic loam remained viable after 10 days as determined by direct counts, but bioassay showed that some conidia remained viable for up to 10 weeks. Seeds from severely diseased cauliflower seedheads contained the pathogen but tests indicated that the disease was not seed-transmitted. P. brassicae was not found on any of the common cruciferous weeds present in vegetable brassica crops in the Pukekohe district. Only summer-grown plants of oilseed rape were susce...