The partial contribution of specific airborne pollen to pollen induced allergy

The air that we inhale contains simultaneously a multiple array of allergenic pollen. It is well known that such allergens cause allergic reactions in some 15 of the population of the Western World. However little is known about the quantitative aspect of this phenomenon. What is the lowest concentration of pollen that might trigger allergic responses? As people are exposed to heterogeneous and variable environments, clarification of the partial contribution of each of the major airborne pollen allergens and determination of its role in invoking allergy are of prime importance. Objectives: (1) Assessment of a possible correlation between the concentration of airborne pollen and incidence of allergy. (2) Estimation of the lowest average concentrations for various species of airborne pollen that elicit allergic symptoms when exceeded. (3) Determination of the extent of the variations in manifestation of allergy symptoms that can be explained by fluctuations in the concentration of individual species of airborne pollen. Methods: The study was conducted during 14months with a rural population in Israel. The participants completed a detailed questionnaire and were skin prick tested with the common airborne allergens. The appearance of clinical symptoms, i.e. nasal, bronchial, ocular or dermal, were reported daily by the patients. Concentrations of the airborne pollen and spores were monitored in the center of activity of the residents during one day every week, using three Rotorod pollen traps. The pollen grains were identified by light microscopy. Results: The pollen spectrum was divided into time-blocks presenting the main pollination periods of the investigated species. The correlation between the concentration of airborne pollen of the relevant species and the clinical symptoms of the patients was determined for each time block. The correlation differed for different clinical symptoms and for different pollen allergens. Highest correlation with airborne pollen counts was found for patients with nasal and bronchial symptoms. The onset of the clinical symptoms by sensitive patients started, in each of the relevant groups, once the weekly average concentration of the airborne pollen crossed a threshold level. Under the limitations of the present study, this level was estimated to be 2–4 pollen m^–3 air for olive, 3–5 pollen m^–3 air for grasses, 4–5 pollen m^–3 air for Artemisia, 10–20 pollen m^–3 air for pecan and 50–60 pollen m^–3 air for cypress. Conclusions: Fluctuations in specific airborne pollen grains explained up to 2/3 of the variation in clinical allergy responses. Those were: 69 of the variation for cypress (March–April), 66 for the grasses (March–April), 49 for the pecan (May–June) and 62 for Artemisia (Autumn).     

Land-use history of Riekkalansaari Island in the northern archipelago of Lake Ladoga,Karelian Republic,Russia

Agricultural history was investigated by means of pollen and charcoal analyses from the sediment of Lake Kirjavalampi in the Riekkalansaari Island, in the northern archipelago of Lake Ladoga, NW Russia (61°44N, 30°46E). Pollen and charcoal stratigraphies, and loss-on-ignition were analysed from a 0–294-cm profile cored from the deepest part of the small lake. The pollen profile was divided into six local pollen assemblage zones Kir 1–6 and dated by three radiocarbon samples. Lake Kirjavalampi was isolated from Lake Ladoga between 1460–1300 b.c., when the River Neva was formed as a new outlet for Lake Ladoga and the water level rapidly fell. The isolation is seen as a phase of rapid sedimentation in Kir 2 (237–173 cm). Spruce (Picea) starts to decline at 113 cm ca. a.d. 70, and the earliest cereal (Secale cereale) pollen was encountered at the 97-cm level, empirically dating the onset of cultivation to ca. a.d. 600. A marked intensification in agricultural activities occurs around a.d. 1200, and the indication of an open cultivated landscape is at its strongest during the time period 1700 to 1850.     

Aırborne pollen calendar of Bartın, Turkey

Our study comprises airborne pollen analysis of the years 1995–1997 of Bartn (40°38 N–32°21 E). The aims of the study were: to determine the pollen types present in the atmosphere, to calculate their actual concentrations, and to establish the pollen calendar for Bartn. For this purpose, pollen slides of Durham apparatus, which was located in four different locations in Bartn, were examined on a weekly basis. In this study, 19062 pollen grains were counted and 18484 of those were determined on the slides in the air of Bartn during three years of period. Results show that 13758 of 18484 pollen grains belong to arboreal, 4726 belong to non-arboreal taxa. 3698 of determined non-arboreal taxa belong to Gramineae.     

Viability and sunlight sensitivity of oak pollen and its implications for pollen-mediated gene flow

Pollen-mediated gene flow and the male reproductive success of wind-pollinated trees depend on the initial viability of the pollen and the changes that occur in its viability during transport in the atmosphere. The viability of Quercus robur pollen was determined before and during exposure to sunlight by in vitro germination and the fluorescein diacetate reaction (FCR) in 2002 and 2003, respectively. These experiments allowed us to calculate initial pollen viability and pollen sensitivity to sunlight. The germination test revealed a lower initial pollen viability (25–65%) than the FCR (53–92%). Following 9.5 h of irradiation the viability was reduced to 75–100% as determined by the in vitro germination test or to 40–70% as determined by the FCR. The actual values of initial pollen viability and pollen sensitivity to sunlight were used to define a range of values for modelling pollen dispersal using the mesoscale meteorological model METRAS. The deposition patterns of viable pollen varied by as much as a factor of 14 by changing the viability parameters in the range of the observed values. This suggests significant differences in male reproductive success. Variations in initial pollen viability have stronger effects on the gene-flow pattern than do variations in pollen sensitivity to sunlight. In particular, pollen distribution throughout the local environment is shaped by the initial pollen viability, while pollen sensitivity to sunlight mainly influences long-distance pollen dispersal.This revised version was published online in February 2005 with corrections to an incorrect sentence in the Results section. Under Pollen Sensitivity it should read: decreased faster when assessed by the germination test than by the FCR.     

Prey capture by three Pinguicula species in a subarctic environment

The number and biomass of prey captured were estimated for Pinguicula alpina, P. villosa and P. vulgaris in a subarctic environment. Seasonal captures were estimated for one site per species for 4–5 years. Captures were related to reproductive status (reproductive/non-reproductive) and to leaf area. For one species (P. vulgaris) the catch was also compared across a range of habitats. Of the seasonal catch, 50–75% was obtained during June and less than 5% during August. For P. alpina and P. villosa the seasonal catch varied threefold or more between years (means of 89–329 g dry matter plant^–1 season^–1 for P. alpina, and 11–91 g dry matter plant^–1 season^–1 for P. villosa), whereas the between-year variation for P. vulgaris was small (mean c. 600 g plant^–1 season^–1). Large variations were, however, observed among habitats for P. vulgaris. Captured prey may contribute a substantial amount of nutrients to the most successful individuals (up to 85% of the mean seasonal turnover), but prey capture varied greatly and during any given season many individuals obtained only marginal amounts of nutrients through carnivory. P. vulgaris trapped almost twice as much per unit leaf area and season as the other two species (224 for P. vulgaris versus 127 g cm^–2 season^–1 for the other two species). Reproductive individuals of P. vulgaris trapped almost twice as much as non-reproductive individuals (after taking differences in leaf area into account). For the other two species no differences were observed between reproductive and non-reproductive individuals.     

Analysis of meiosis in triticale (XTriticosecale Wittmack) X rye (Secale cereale L.) F1 hybrids at three ploidy levels

Summary Triticales (XTriticosecale Wittmack) at three ploidy levels (8x, 6x, 4x, x=7) were crossed with diploid rye (Secale cereale L.) to produce a solitary hypopentaploid hybrid (2n=32), and a number of tetraploid (2n=4x=28) and triploid (2n=3x=21) hybrids. The hybrids exhibited a morphology which was intermediate between the parents. The number of bivalents ranged from 1–7 (4.65 per cell) in hypopentaploid, from 2–12 (7.13 per cell) in tetraploid and from 4–9 (6.84 per cell) in triploid hybrids. In 4x and 3x hybrids, trivalents and quadrivalents were also observed at low frequencies (range 0–1; mean 0.01–0.03 per cell). Chiasmata frequency was highest in triploid hybrids (12.44 per cell), lowest in hypopentaploid (5.37 per cell) and intermediate in tetraploids (10.54 per cell). More than 7¹¹ were found in 39.7% pollen mother cells (PMC's) in the 4x hybrids and in 5.0% PMCs in 3x hybrids. It is concluded that an increase in the relative proportion of wheat chromosomes in the hybrids had a slight suppression effect on homologous as well as homoeologous pairing of rye chromosomes. Contrary to this, the relative increase in rye complement promoted homoeologous pairing between wheat chromosomes. In triploid hybrids, the chiasmata frequency as well as the c value were the highest, suggesting that in tetraploid hybrids rye chromosomes had a reduced pairing (low frequency of ring bivalents).     

The Effect of Concanavalin A on Membrane Potential and Intracellular pH during Activation In Vitro of Tobacco Pollen Grains

We studied the effects of short-term (5–10 min) treatment of Nicotiana tabacum L. pollen grains with concanavalin A (ConA) on their activation (changes in the membrane potential and intracellular pH) and germination in vitro. ConA (10–1000 g/ml) induced plasma membrane hyperpolarization in the vegetative cell and enhanced pollen grain germination. These effects depended on ConA concentration and were interrelated: the value of the membrane potential was negatively correlated with the number of pollen grains germinated for 1 h of their incubation (r = –0.96). In addition, ConA (100 g/ml) increased the intracellular pH value by 0.3 unit. All these effects of ConA are determined by its specific interaction with carbohydrate determinants because a competitive sugar methyl--mannopyranoside (0.1 M) completely blocked ConA effects. The data obtained presume that the specific receptors are present on the surface of pollen grains, evidently on their plasma membrane, and their interaction with lectins has a functional significance for pollen grain activation and germination.     

Concentration of airborne pollen of Vitisvinifera L. and yield forecast: a case study at S.Michele all'Adige,Trento, Italy

The possibility of creating a forecast model for grapeproduction using airborne pollen concentrations ofVitis vinifera L. was investigated. The studyarea is located in the province of Trento (46°11,11°08), North Italy. Because of its prestigious wineproduction, the area is quite important on a nationalscale.Airborne pollen concentration data (P/m³) werecollected for a five year period (1993–1997) with aHirst type sampler (VPPS 2000 – Lanzoni) following thestandard methodology proposed by the ItalianAeroallergen Network. For the same five-year period,grape production data (kg/ha) from vineyards adjacentto the pollen sampler were used along with provincialdata. Regression lines were constructed using the Lnof the annual sum of daily pollen concentrations (Ip)as the independent variable and grape productionvalues as the dependent variable. Correlations betweenpollen data (pollen index, beginning and duration ofmain pollen season) and meteorological data(temperature and rainfall) are shown.     

The long-range transport of Pinaceae pollen: an example in Kraków (southern Poland)

High Pinaceae pollen concentrations in the air and on the surface of puddles before the main pollen season started were observed in Kraków (southern Poland) in May 2013. The paper presents the results of detailed studies of the composition and source of the “yellow rain” in 2013, and as a comparison, the Pinaceae pollen concentrations and samples collected from the ground surface in 2014 were considered. The air samples were collected using the volumetric method (Hirst-type device), while pollen grains sampled from the ground surface were processed using a modified Erdtman acetolysis method. Finally, all samples were studied using a light microscope. In 2013, the period of higher Abies, Picea and Pinus pollen concentrations was observed from the 5 to 12 of May, earlier than the main pollen season occurred. The presence of rainfall on the 12 and 13 of May 2013 caused the pollen deposition on the ground surface, where the prevalence of Pinaceae pollen was found. The synoptic situation and the analysis of the back-trajectories and air mass advection at the beginning of May 2013 indicated that Pinaceae pollen grains could have been transported from Ukraine, Romania, Hungary and Slovakia. In contrast, Pinaceae pollen grains deposited on the ground surface as a “yellow” film in May 2014, originated from local sources.     

The timing and effectiveness of sequential pollinations in Hibiscus moscheutos

In many species with animal-pollinated flowers, pollen arrives on the stigma in pulses and late-arriving pollen may be precluded from fertilizing ovules. When seed set per fruit is not pollen limited, the fate of pollen from later cohorts is affected by the time between pollinator visits, variation in pollen tube growth rates, and the amounts of pollen deposited relative to the availability of stigmatic area and unfertilized ovules. In a natural population of Hibiscus moscheutos, we found that consecutive pollinator visits to individual flowers occurred within 15 min of each other in more than half of our observations. We then conducted hand-pollination experiments using equal doses of early and late pollen bearing unique allozyme markers for paternity analysis (each dose was more than sufficient to result in full seed set). When pollen was applied 15 or 30 min after an earlier pollen load, the proportions of seeds sired by late-arriving pollen were reduced by 13–30% and 21–57%, respecitively. A few pollen-tubes from the late pollen load sired seeds even when a large dose of pollen was applied 1–2 h earlier, suggesting that the performance of pollen grains within each cohort was highly variable. The advantage of arriving early was greater when the first pollen load was applied at 0930 hours as compared with 1130 hours. We found no effect of previous pollination on the growth rates of late-arriving pollen-tubes. Taken together, these results demonstrate that pollen from later visits can compete with pollen from earlier visits, but the success of late-arriving pollen typically declines to very low levels after an interval of about 2 h. Given that surplus pollen often arrives on stigmas by mid-morning, we conclude that male reproductive success is more likely to be affected by the timing of pollen dispersal and pollen-tube competitive ability than by the total amount of pollen that is exported from flowers.     

A comparison of Betula pollen seasons at two European sites; Derby, United Kingdom and Poznan, Poland (1995–1999).

A comparison of Betula pollen, animportant European aeroallergen, was undertakenat two sites of similar latitude, Derby, UnitedKingdom and Poznan, Poland from 1995–1999. Bothsites routinely monitor Betula pollenusing a Burkard continuous volumetric sampler.Daily and two-hourly March–June Betulapollen counts per cubic metre of air werestudied at both sites, together withcorresponding meteorological data. Detailedanalysis was undertaken to compare start dates,duration and quantity of Betula pollen.Derby usually had an earlier start of seasonthan Poznan, and both cities showed very littledifference between start dates determined byusing the SUM 75 or 2.5% method. The longestseasonal durations at Derby and Poznan yieldedthe lowest seasonal pollen indexes. Every yearfrom 1995–1999 the Betula seasonal pollenindex was higher in Poznan than in Derby. Poznanhad more daily counts of Betula pollengrains per cubic metre above 500, and at leastone daily count of 1000, each year. At bothsites the yearly seasonal variation correlatedwith the number of April days per year having amaximum temperature of 17 °C or above.There was a similar diurnal periodicity ofApril Betula pollen in Derby and Poznan.Although the two cities, at approximately thesame latitude, have different regional andmeteorological characteristics, the weatherappears to influence Betula pollenseasons in a similar manner. Local clinicianscould use the SUM 75 method as indicative ofthe start of the Betula pollen season atboth sites.     

Pollen callus culture in Triticum aestivum

Summary Pollen shed between 4–8 d from anthers of Triticum aestivum cultured in liquid medium gave rise to calluses. Tillers were harvested at the mid-to late-unicellular pollen stages and chilled for 8 d at 4–5 °C before the anthers were dissected out. Pollen cultures gave about 6 times as many calluses on a per anther basis as anthers cultured on solid medium. With the most productive of 5 cultivars tested, pollen culture results in roughly one callus for each anther used, though the calluses formed by pollen culture were less productive for the regeneration of shoots than calluses derived from anthers cultured on solid medium. The ratio of green to albino shoots is roughly 1 1 for anther cultures but considerably less for pollen cultures.     

A correlation study between airborne pollen and cases of pollinosis in humans

This study aims to establish themathematical relationship between allergenicpollen in the air and clinical cases ofpollinosis (hay fever) in humans, and toevaluate the immediate effect of wind and rainon such cases. The pollen was collected inFigueres, Catalonia, Spain (42°30 Nand 3° E), through a filtration method,in the spring of 1998. Skin tests revealed thatthe antigenic taxa are Olea europaea,Plantago sp., Parietaria officinalisand Gramineae. A linear correlation –with the number of days with presence of pollenas the abscissa and the number of days withcoincidence of pollinosis as the ordinate – wasperformed. The linear correlation coefficientwas 0.9285, at the limit of a directcorrelation by two degrees of freedom.Furthermore, a negative relationship wasobserved between the number of days with rainand number of days with pollinosis, and apositive relationship between the number ofdays with fixed wind speed and number of dayswith pollinosis.     

TheCaMV 35S promoter is highly active on floral organs and pollen of transgenic strawberry plants

We have evaluated the expression of the reporter -glucuronidase (GUS) gene driven by the cauliflower mosaic virus 35S (CaMV 35S) promoter in flowers and pollen from 14 independent transgenic strawberry lines. Of the 14 lines evaluated, 13 (92.8%) showed GUS activity—as estimated by the histochemical GUS assay—in some floral organs, with expression being most common in the flower stem, sepals, petals, ovary and stigma. Ten of these thirteen transgenic lines (77%) showed GUS activity in pollen, although the percentages of positive pollen per flower varied greatly among the different lines. A study of the GUS expression during pollen maturation showed that the (CaMV 35S) promoter showed low expression in pollen from flower buds before anthesis but was activated in mature pollen following anther dehiscence. The percentages of pollen grains that showed GUS activity ranged from 2.1% to 46.3%. These percentages were similar or even higher when mature pollen was stored dry at room temperature for 2 weeks. After 5 weeks of storage, the percentages of GUS-positive pollen decreased in two of the six lines analysed but remained at similar values in the other four lines. GUS activity was also measured in protein extracts of mature pollen by means of the fluorometric GUS assay, with the values obtained ranging from 3.8 mol MU mg protein^–1 h^–1 to 0.26 mol MU mg protein^–1 h^–1. Contrary to the generally held view that the CaMV 35S promoter is virtually silent in pollen, we conclude that it is highly expressed in transgenic strawberry pollen.Abbreviations CaMV 35S Cauliflower mosaic virus promoter - GUS -Glucuronidase (EC 3.2.1.31) - MU 4-Methyl umbelliferone - nos Nopaline synthase promoter - nptII Neomycin phosphotransferase - X-Gluc 5-Bromo-4-chloro-3-indolyl--d-glucuronic acid     

Energy conservation during aerobic growth in Paracoccus denitrificans

Paracoccus denitrificans was aerobically grown in chemostat culture with succinate or gluconate as carbon source. Due to the presence of two phosphorylation sites in the respiratory chain and the absence of branching, theoretical P/O ratios of 1.71 and 1.82 were calculated for cells growing respectively with succinate and gluconate as carbon source. Using these data, 95% confidence intervals for the P/O ratio were determined, via a mathematical model, at 0.91–1.15 and 1.00–1.37 for sulphate-limited cultures, with respectively succinate and gluconate as carbon source.These results and measurements of P/O ratios in membrane particles and of proton translocation in whole cells have led to the conclusion that site I phosphorylation is affected under sulphate-limited conditions.Under conditions of carbon source-limitation the endogenous H⁺/O ratio is about 7–8. Average values of 3.40 and 4.78 were respectively found for sulphate-limited succinate- and gluconate grown cells. For starved cells, oxidizing succinate as exogenous substrate, the H⁺/O ratios were determined at about 3–4, independent of the growth limiting factor. It is concluded that the number of protons ejected per pair of electrons per energy-conserving site (H⁺/site ratio) is about 3–4, instead of 2 as postulated by the chemiosmotic hypothesis.     

Pollen irradiation and gene transfer in Capsicum

Summary The aim of the experiment was to study the possibility of facilitating the gene transfer and reducing the number of required backcrosses through pollen irradiation and subsequent selection of F₁M₁ plants containing a very high proportion of sterile pollen as male parent for backcrossing. Anthers of a donor line, C-3-1, were irradiated with 1,500 rad -rays and the pollen used for pollination of a recipient genotype W-8 which posseses a number of recessive marker genes. Five F₁M₂ plants containing more than 80% sterile pollen grains and one semi-sterile plant were selected and used for backcross to W-8. The segregation pattern of four characters expressed in the first backcross generation [W–8×(W–8×C–3–1)] was assessed and compared with the non-irradiated control. A changed segregation pattern was observed (in some cases even non-transfer of a paternal allele) as well as a shift towards more plants possessing the investigated maternal alleles. A scheme for backcross procedure in combination with pollen irradiation is discussed.     

Variation in Ambrosia pollen concentration in Southern and Central Poland in 1982–1999

The aim of the study was to investigate theAmbrosia pollen concentrations inselected Polish cities and for Kraków torelate it to some meteorological factors.Sampling was carried out in Kraków in1982–1997 and in Rabka in 1992–1996 with theuse of the gravimetric method. In Zakopane,Kraków, Ostrowiec witokrzyski,Warszawa and Pozna in 1995–1996 both thegravimetric and volumetric methods (Burkardtrap) were employed. In Kraków themonitoring has been performed since 1994 usingthe volumetric method. The results show theragweed pollen presence in August and Septemberwith the tendency to appear more frequently inAugust in some years. In Kraków (1994–1999)Ambrosia pollen was found either in thelast two weeks of August or in the first twoweeks of September which seems to be a regularand repeatable pattern every two years.Seasonal fluctuations of Ambrosia pollenconcentration do not show a clear increasingtendency except at Warszawa and Ostrowiecwitokrzyski in 1996 and at Krakówin 1999. Percentage of Ambrosia pollen inannual sums of total pollen is very low anddoes not exceed 1% except at Ostrowiecwitokrzyski in 1996 (1.2%) and atKraków in 1999 (2%). For Kraków theanalysis of some meteorological factors (Tmax,Tmin, precipitation, wind direction) wasperformed. High temperature and lack of rain orlow precipitation correlate well with ragweedpollen concentrations. During the Ambrosia pollen seasons ESE, E, S, SE, WSW, SWwind directions prevailed which could suggest along-distance transport from Ukraine, the CzechRepublic, Slovakia and also from Hungary, one ofthe most ragweed-polluted countries.     

Regional and extra-local pollen in Tundra pollen samples

Patterns of pollen spectra formation in the tundra zone of Eurasia were considered. Changes in total pollen concentration were traced in subfossil pollen samples of the tundra zone. The data on subfossil pollen spectra were used to evaluate the proportion between local and regional plus extra-local components of tundra pollen samples as well as the changes in concentration of pollen of Scots and Siberian stone pines as well as of tree and shrub birches. The diameter of dwarf birch pollen was determined in different tundra subzones of Western Siberia. The role of extra-local and regional pollen was considered for all vegetation subzones of tundra.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 88–99.Original Russian Text Copyright © 2005 by Vasilchuk.     

Accumulation and turnover of 2-tridecanone in Tetranychus urticae and its consequences for resistance of wild and cultivated tomatoes

In this study we assessed the dynamic changes of 2-tridecanone in a herbivorous mite (Tetranychus urticae) on tomato (Lycopersicon esculentum, cv. Moneymaker), a plant with methyl ketones in the tetracellular tips of the glandular trichomes (Type VI). We showed that spider mites accumulate 2-tridecanone when foraging on cultivated tomato. Thus, the rate of mite–trichome contact multiplied by the amount of toxin per trichome tip exceeded the relative rate of toxin turnover multiplied by the amount of toxin per mite. The relative rate of toxin turnover was estimated to be 1.1 per day on cucumber, a plant without this toxin. The amount per trichome tip varied from 0.33 ng for middle-leaf trichomes to 1.26 ng for main-stem trichomes. Hence, to achieve a static level of 2-tridecanone equal to 8–17 ng per mite – representing the level we found in mites on middle leaves – the rate of mite–trichome contact should be 26–57 per day. Because methyl ketone apparently accumulates in the spider mites on tomato, the rate of mite–trichome contact is probably higher than that. We expect the accumulation of ketones to occur especially on the stems of cultivated tomato, since this is the area most densely occupied with glandular hairs and because here the hairs have higher levels of the methyl ketones.Using dose–response relationships assessed earlier (Chatzivasileiadis and Sabelis, 1997, 1998), we estimated that the number of mite–trichome contacts causing 50% mortality per day is equal to 88 on a tomato stem, whereas it equals 70 for another strain of spider mites collected from cucumber. On wild tomato, L. hirsutum f. glabratum (PI 134417), just one to two contacts would suffice to cause 50% mortality per day. We suggest that methyl ketones from glandular hairs on tomato are an important mortality factor for spider mites on wild tomato and probably also on cultivated tomato.     

A study of Quercus pollen in the Derby area, UK

The major allergenic pollen prevalent in the Derby air in May is Quercus pollen which has been monitored volumetrically from 1970–1997. Quercus pollen levels in Derby are increasing, showing an established long term trend, with 1995 being an exceptionally high year. There is now an earlier start date and a longer seasonal duration. The mean Quercus diurnal periodicity for 1991–1997 shows a peak at 15.00 hours.A detailed study of the 1990–1997 seasons established that a maximum temperature of 20 °C or above, at the usual time of flowering, occasions the start of the Quercus pollen season. Average May temperature and drought in the previous June and July are important factors in determining Quercus pollen totals. Predictions for the forthcoming seasons were produced which compared favourably with the actual pollen totals.