Biology of Striga hermonthica (Scrophulariaceae) in Sahelian Mali: effects on pearl millet yield and prospects of control

Aspects of the population: dynamics of Striga hermonthica (Del.) Benth. on pearl millet (Pennisetum americanum (L.) K. Schum.) were studied in Sahelian Mali. Seasonal development was recorded and density-dependent mortality and fecundity in post-emergent populations investigated. An attempt was also made to assess yield loss due to S. hermonthica attack using a regression approach. The first S. hermonthica plants emerged 42 days after crop germination, and the minimum time to complete the life cycle from emergence was 56 days. Results indicated a premature mortality of 66% in emerged populations. The growth stage reached by the time of host plant death appeared to be important in determining survival to maturity, premature mortality being greatest in plants that had not reached flowering by this time. The potential seed output per plant was estimated at 10 985. There was no evidence that the fecundity of S. hermonthica was affected by the density of emerged populations. Regression models showed a significant relationship between millet yield and emerged S. hermonthica density. The results suggest that lower densities give a relatively larger decrease in yield per S. hermonthica plant. The results of the study are discussed in relation to their implications for control.     

Foliar absorption and translocation of nicosulfuron and rimsulfuron in five annual weed species

Ambrosia artemisüfolia L. (common ragweed) and Digitaria ischaemum Schreb. (smooth crabgrass) are not controlled by nicosulfuron and rimsulfuron at the highest recommended application rates, whereas Panicum miliaceum L. (wild proso millet), Amaranthus retroflexus L. (redroot pigweed) and Avena fatua L. (wild oat) are susceptible. The foliar absorption and translocation of ¹⁴C-nicosulfuron and ¹⁴C-rimsulf uron were studied in these weed species up to 48 h after treatment (HAT). Differences in herbicide uptake and translocation were not correlated with the species susceptibility. By 48 HAT, more than 50% of both herbicides remained on the treated leaf surface. Foliar absorption of rimsulfuron was greater than that of nicosulfuron in A. retroflexus, P. miliaceum and A. artemisüfolia. Most of the absorbed herbicide remained in the treated leaf of each weed species. Export of ¹⁴C–nicosulfuron ranged from 28 to 54% of that absorbed, in contrast to 15 to 39% for ¹⁴C–rimsulfuron. The absorption and translocation rates of both herbicides were highest within the initial 6 HAT, and decreased thereafter. Both herbicides showed approximately the same distribution pattern within each weed species.     

An in-vitro growth system for studying the parasitism of cowpea (Vigna unguiculata) by Striga gesnerioides

An in-vitro growth system for investigating the behaviour of S. gesnerioides on cowpea has been developed. The roots of young cowpea plants were spread over glass fibre filter paper in a shallow plastic tray, and a known number of germinated Striga seeds were placed on the cowpea root surface. This allowed the infection process of the parasite to be quantified. Good access to the host-parasite association enabled the entire infection process to be easily monitored and tissue removed for cytological studies. Observations revealed for the first time that contact of S. gesnerioides radicles with host roots stimulated the development of radicular hairs and swelling of the tip of these radicles. Furthermore, penetration of cowpea roots by Striga was shown to be localized and to cause very little damage to the host roots. Swollen parasite tubercles developed on the surface of the roots only after the host stele had been penetrated by invading Striga cells. This growth system is suitable for in-vestigating the mechanisms of host resistance. and also for rapidly screening cowpea germplasm for new sources of resistance to the Parasite. Resistant cowpea cultivars offer the best potential solution for control of this Parasite.     

14C-glyphosate absorption and translocation in germinating maize (Zea mays) and soybean (Glycine max) seeds and in soybean plants

¹⁴C-glyphosate (N-(phosphonomethyl)glycine) uptake by germinating maize (Zea mays L. ‘PAG SX56’) or soybean (Glycine max (L.) Merr. ‘Williams’) seeds from sterile quartz sand was minimal on a weight basis until the radicle became functional. Uptake in soybean seedlings was ten times greater (on a weight basis) than in maize. Germination of either species was not affected by glyphosate concentrations up to 10^?3m , but seedling axis elongation was inhibited in soybeans at 10^?4m and in maize at [0^?3m When ¹⁴C-glyphosate was applied to the fully expanded first trifoliolate soybean leaf (assimilate-exporting), movement into root and shoot assimilate sinks occurred. About 7% of the total ¹⁴C-glyphosate applied was absorbed and translocated into other parts of the plant by 48 h. Of the total ¹⁴C accumulated by 48 h in the roots and apical meristem, nearly 50% was present by 12 h. Minor phytotoxicity resulted from 10 nmoles of glyphosate in the plant. Absorption et migration du ¹⁴ C-glyphosate chez le maïs (Zea mays) en germination et chez les semences et les plantes de soja (Glycine max) L'absorption du ¹⁴C-glyphosate (N-(phosphonométhyle) glycine)par du maïs en germination (Zea mays L.,‘PAG SX56′)ou par des semences de soja (Glycine max (L.) Merr.,‘Williams’) a partir de sable de quartz stérile a été minimale (sur la base du poids) jusquà ce que la racine devienne fonctionnelle. L'absorption par des plantules de soja a été, sur la base due poids, 10 fois plus grande que chez le maïs. La germination de ces deux espèn n'a pas été affectée par des concentrations de glyphosate allant jusquà 10^?3m , maïs l'élongation des plantules a été inhibée chez le soja á 10^?4m et chez le maïs à 10^?3m . Lorsque le ¹⁴C-glyphosate a été appliqué sur la première feuille trifoliée de soja pleinement dévdoppé (en état d'exporter des métabolites). une diminution du mouvemem des métabolites vers les jeunes pousses et vers les racines s'est manifestée. Eaviron 7% du ¹⁴C-glyphosate total appliqué a été absorbé et a migré dans d'autres parties de la plume en 48 heures. Près de 50% du ¹⁴C total accumulé dans les racines et le méristème apical y était présent en 12 heures. Une faible toxicité a réulté de b présence de 10 nmoles de glyphosate dans la plante. ¹⁴ C-glyphosat-Aufnahme und -Translokation bei keimenden Samen von Mais (Zea mays) und Sojabohnen (Glycine max) und bei Sojabohnenpflanzen Die Aufnahme von ¹⁴C-Glyphosat (N-(Phosphonomethyl)glycin) aus sterilem Quarszsand durch keimende Samen von Mais (Zea mays L.‘PAG SX56′) und Sojabohnen (glycine max (L.) Merr.‘Williams’) war, bezogen auf das Pflanzengewicht, bis zur Funktionsaufnahme der Keimwurzel, gering. Die Aufnahme war bei den Sojabohnenkeimlingen zehnmal grösser (Gewichts-basis) als bei Mais. Die Keimung wurde bei beiden Arten durch Glyphosat bis zu 10^?3m nicht beeinflusst. Das Streckungswachstum des Stengels wurde aber bei der Sojabohne bei 10^?4m und beim Mais bei 10^?3m gehemmt. Wenn ¹⁴C-Glyphosat auf das erste vollstándig entwickelte dreibláttrige Sojabohnenblatt (Assimilate exportierend) appliziert wurde, konnte ein Transport in die Assimilatesinks der Wurzel und des Sprosses beobachtet werden. Nach 48 h waren etwa 7% des applizierten ¹⁴C-Glyphosats aufgenommen und in andere Teile der Pflanze transloziert. Vom gesamten nach 48 h in den Wurzeln und im apikalen Meristem akkumulierten ¹⁴C waren fast 50% bereits nach 12 h vorhanden. 10 nmol Glyphosat in den Pflanzen waren nur geringfügig phytntoxisch.     

Infection of the pearl millet (Pennisetum americanum) inflorescence by the downy mildew fungus (Sclerospora graminicola)

Different developmental stages of the inflorescence of pearl millet (Pennisetum americanum) were inoculated with zoospores of the downy mildew fungus (Sclerospora graminicola). Individual florets within a panicle were infected, with resultant malformation of any floral organs that were not fully differentiated at the time of infection. 'Green-ear' symptoms resulting from hyperplasia and hypertrophy of the host tissues were accompanied by both sexual and asexual sporulation of the fungus on the malformed plant parts. No grain set occurred in affected florets, indicating that secondary inoculum was able to cause yield reductions even at late stages in the host development. Infection of differentiated stigmas led to rapid dissolution and necrosis of tissue and prevented colonization by the pathogen. This failure suggests that seeds are unlikely to be infected internally.     

ALMANAC 模型对黄土高原玉米、谷子和糜子产量的模拟

用ALMANAC作物模型对黄土高原安塞县大南沟小流域2000～2004年玉米、谷子和糜子的产量进行模拟.结果显示,ALMANAC模型能够很好地模拟该地区的粮食产量,模拟值与实测值回归方程的决定系数大于0.72,回归方程接近1∶1线.玉米、谷子和糜子模拟产量与实测产量之间的平均相对误差分别为-2.29%、-2.32%和8.34%,模拟产量与实测产量之间的标准化均方根差分别为15.7%、11.5%和15.8%.梯田、阴坡和阳坡之间的模拟误差有所差异,玉米梯田产量的模拟值比实测值偏高,阴坡和阳坡产量的模拟值偏低;谷子梯田和阴坡产量的模拟值偏低,阳坡产量的模拟值偏高;糜子梯田和阳坡产量的模拟值偏高.梯田模拟值与实测值之间的一致性较好,其次为阴坡,再次为阳坡.     

Foliar absorption and translocation of fosamine and 2,4,5-T in blackberry (Rubus proceras P. J. Muell.)

Fosamine (ammonium ethyl carbamoylphosphonate) formulated as a 1% w/v solution in 0–25%v/v Tween 20 was absorbed slowly by detached leaves of Rubus procerus P.J. Muell., 35% of the applied herbicide being absorbed after 96 h. Fosamine does not appear to be rainfast, as up to 80% of the applied herbicide and 99.9% of the removable herbicide were removed from the leaves by washing for 5 min in distilled water. Translocalion of fosamine was rapid in small R. procerus plants and followed a pattern similar to that taken by assimilates: 2,4,5–T did not translocate to the root system as readily as fosamine or assimilates.     

大盾象属的种类、分布、寄主及其检疫重要性(鞘翅目:象虫科)

大盾象属(Magdalis Germar,1817)已记录种类95种,分布于古北区的71种,25种分布在新北区。大盾象属既危害针叶树,也取食阔叶树,其寄主植物包括36个属71种。美洲的25种、俄罗斯31种中的22种、日本的8种,在我国均没有分布,是我国检疫工作需要关注的重点种类。     

The arbuscular mycorrhizal host status of plants can not be linked with the Striga seed-germination-activity of plant root exudates

Journal of Plant Diseases and Protection - Root exudates from sorghum, a Striga and arbuscular mycorrhizal fungal (AMF) host plant, and a number of Striga non-host plants which are AM host or AM...     

豆野螟对寄主的选择性及豇豆品种抗螟性比较

研究了豆野螟(Maruca testulalisGeyer)对豇豆、扁豆、普通菜豆3种寄主植物的选择性,以及30个豇豆品种对豆野螟的抗性。结果表明普通菜豆的花与荚的虫量均为零,豆野螟对普通菜豆表现出明显的不选择性,对豇豆和扁豆表现出明显的嗜食性,但对扁豆则更偏食,扁豆与豇豆在豆荚中的幼虫虫量存在极显著差异。豇豆不同品种的抗螟性也存在一定差异,高产4号等5个品种较为感虫,而云优油青、惠丰8号、8月冬求3个品种对豆野螟有较高的抗性且与其他品种存在极显著差异。     

豆野螟对寄主的选择性及豇豆品种抗螟眭比较

研究了豆野螟(Maruca testulalisGeyer)对豇豆、扁豆、普通菜豆3种寄主植物的选择性,以及30个豇豆品种对豆野螟的抗性。结果表明普通菜豆的花与荚的虫量均为零,豆野螟对普通菜豆表现出明显的不选择性,对豇豆和扁豆表现出明显的嗜食性,但对扁豆则更偏食,扁豆与豇豆在豆荚中的幼虫虫量存在极显著差异。豇豆不同品种的抗螟性也存在一定差异,高产4号等5个品种较为感虫,而云优油青、惠丰8号、8月冬求3个品种对豆野螟有较高的抗性且与其他品种存在极显著差异。     

Herbaceous host plants for the sharka (plum pox) virus

A number of 75 species belonging to 18 families were tested for their susceptibility and sensitivity to the sharka virus of plum using sap from infectedNicotiana clevelandii leaves; 27 species out of 6 families were found to be new hosts. OnlyRanunculus arvensis may serve as a new test plant. Common weeds and garden plants were among the newly found host plants.Lamium amplexicaule andZinnia elegans became systemically infected. In the glasshouse the virus was transmitted byMyzus persicae from peach seedlings toL. amplexicaule and vice versa. If transmitted in the field as easily as in the glasshouse, elimination of the virus might be very difficult.Samenvatting Uit 18 families werden 75 plantesoorten getoetst op hun vatbaarheid en gevoeligheid voor het sharka-virus van de pruim. De planten werden geïnoculeerd met het sap van geïnfecteerde topbladeren vanNicotiana clevelandii; 27 soorten uit 6 families bleken vatbaar voor het virus. AlleenRanunculus arvensis is wellicht een bruikbare toetsplant. Onder de pas gevonden waardplanten van het sharka-virus bevinden zich ook enkele algemeen voorkomende onkruiden en tuinplanten.Lamium amplexicaule enZinnia elegans werden systemisch door het virus geïnfecteerd. In de kas kon het virus met behulp vanMyzus persicae worden overgebracht van perzikzaailingen naarL. amplexicaule en omgekeerd. Indien de overdracht in de natuur even gemakkelijk verloopt als in de kas, dan kan dit het uitroeien van het sharka-virus in besmette gebieden ernstig bemoeilijken.     

Retention,absorption, translocation and distribution of sethoxydim in monocotyledonous and dicotyledonous plants*

Quackgrass [Elymus repens (L.) Gould =Agropyron repens (L.) Beauv.] and barnyardgrass [Echinochloa crus-galli (L.) Beauv.] were more than one hundred times more susceptible to sethoxydim than alfalfa (Medicago sativa L. 'Saranac') or navybean (Phaseolus vulgaris L. 'Seafarer'). Uptake of sethoxydim From soil following post-emergence applications caused negligible reduction in E. crus-galli fresh weight. More than 80% of foliar-applied ¹⁴C-sethoxydim was absorbed within 6 h in all species. Translocation occurred in all species with accumulation of ¹⁴C in rapidly growing plant tissues. Translocation to the roots was less than 8% of total in all species. Most of the extracted ¹⁴C initially partitioned into an ethyl acetate-soluble fraction. The proportion of ¹⁴C in the ethyl acetate-soluble fraction decreased with time with a concomitant increase of that in the insoluble fraction. Differences in the quantity of ¹⁴C in the ethyl acetate-soluble fraction did not account for the observed selectivity.     

烟粉虱成虫对不同寄主植物的选择性

选用棉花、烟草、番茄、甘蓝进行非选择性和选择性试验研究 ,探讨烟粉虱成虫对 4种寄主植物的嗜食性。结果表明 ,在 4种寄主作物共同存在时 ,烟粉虱成虫喜欢取食烟草 ,排列顺序为 :烟草 >番茄 >棉花、甘蓝 ;产卵量排列顺序为 :烟草、番茄 >甘蓝、棉花。当只有番茄和烟草两种寄主植物时 ,烟粉虱成虫趋向于取食烟草 ,但在番茄上产卵 ;只有烟草和甘蓝时 ,烟粉虱倾向于取食烟草并产卵 ;只有棉花和番茄时 ,烟粉虱对两种寄主没有明显的趋向 ;只有棉花和烟草时 ,烟粉虱显著的喜好在烟草上产卵 ;只有棉花和甘蓝时 ,烟粉虱趋向在棉花上取食产卵 ,但没有达到显著水平 ;同样只有番茄和甘蓝时 ,烟粉虱喜好在番茄上取食产卵 ,但没有达到显著水平。     

Formulation and adjuvant effects on the absorption and translocation of 14C-clethodim in wheat (Triticum aestivum L.)

A new formulation of clethodim {(E,E)-(±)-2-(1-[([3-chloro-2-propenyl]oxy)imino]propyl)-5-(2-[ethylthio]propyl)-3-hydroxy-2-cyclohexen-1-one} is labeled for the control of grasses and volunteer grass crops, including glyphosate-resistant corn. The effects of the formulation (new: 0.12 kg L⁻¹ and current: 0.24 kg L⁻¹) and adjuvants (ammonium sulfate [AMS], crop oil concentrate [COC] or both) on the absorption and translocation of the ¹⁴C-clethodim was determined at 1, 4, 12, 24, 48, and 72 h after treatment (HAT) in wheat under greenhouse conditions. The absorption of the ¹⁴C-clethodim with the 0.12 kg L⁻¹ formulation was higher than that with the 0.24 kg L⁻¹ formulation, especially at 24 HAT and beyond, regardless of the presence or absence of an adjuvant. The addition of an adjuvant increased the absorption of the ¹⁴C-clethodim with the 0.12 kg L⁻¹ formulation at all harvest times, except at 72 HAT. However, there were no differences in the ¹⁴C-clethodim absorption among the adjuvants added to the 0.12 kg L⁻¹ formulation, except at 48 and 72 HAT. Most of the ¹⁴C-clethodim remained in the treated leaf independent of the formulation or adjuvant. The formulation did not have an impact on the distribution of the absorbed ¹⁴C-clethodim; however, the presence of an adjuvant increased the movement of the ¹⁴C-clethodim out of the treated leaf. Most of the absorbed ¹⁴C-clethodim remained in the treated leaf and a negligible amount translocated to the root. These results demonstrated the improved absorption of clethodim with a formulation containing half of the active ingredient (0.12 kg L⁻¹) and the inclusion of both AMS and COC.     

Synthesis and anti-mildew activity of 5-(2-aroyl)aryloxymethyl-2-phenyl-1 ,3,4-oxadiazoles against downy mildew of pearl millet

A manipulatively simple, rapid, high-yielding and environmentally benign method for the integration of a heterocyclic ring, 1,3,4-oxadiazole, at the benzophenone nucleus has been achieved through intramolecular cyclization of substituted aroylaryloxyacetohydrazides to substituted 5-(2-aroyl)aryloxymethyl-2-phenyl-1,3,4-oxadiazoles under solventless 'dry' conditions using montmorillonite K10 clay and microwave irradiation. A comparison is made of the microwave-accelerated reaction with conventional heating conditions. Certain of the derivatives tested showed significant anti-mildew activity against Sclerospora graminicola (Sacc) Schroeter, the downy mildew pathogen of pearl millet.     

Estimation of the seedbank of Striga spp. (Scrophulariaceae) in Malian fields and the implications for a model of biocontrol of Striga hermonthica

Striga seeds were extracted from soils collecled in Mali and the viahility of these seeds was estimated. Striga seeds were found in 45 of 46 samples taken from 23 fields. Siriga hermonthica (Del.) Benth. growmg on the host crop millet, was present at all 46 sites sampled. The a size uf the Striga seedbaiik measured lo a depth of 15 cm was estimated to be 38 800 m ^-2 of surface area (geometnc mean 11 500). The average number of S. hermonthica plants observed per millei hill was 8.83 (geometric mean 3.89) or 13.98 m^-2 (gcometrie mean 5.69 m^-2). Higher crop hill densities tended to result in higher densities of emerged S. hermonthica per hill. The relationship between seeds m^-2 and S. her-monhica plants m^-2 was fitied to a reetungular hyperbola and used to reassess an existing model of S. herniouhica control.     

Comparison of efficacy, absorption and translocation of three glyphosate formulations on velvetleaf (Abutilon theophrasti)

Growth analysis, absorption and translocation studies were conducted to compare a 1-aminomethanamide dihydrogen tetraoxosulfate (GLY-A) formulation of glyphosate with two isopropylamine (GLY-IPA-1, GLY-IPA-2) formulations of glyphosate on velvetleaf. The two isopropylamine formulations differed by the presence of a surfactant in the formulation, GLY-IPA-1 containing surfactant whereas GLY-IPA-2 did not. Four- to six-leaf velvetleaf was treated with GLY-A and GLY-IPA-1 and GLY-IPA-2 (0, 50, 67, 89, 119, 158, 280, 420, 560 and 840 g AE ha(-1)) with and without ammonium sulfate (AMS; 20 g L(-1)). GLY-A and GLY-IPA-2 included a non-ionic surfactant (2.5 mL L(-1)) in the spray solution at all herbicide concentrations. No additional surfactant was added to GLY-IPA-1. The IC50 value for GLY-A was 88 g AE ha(-1) compared with 346 and 376 g AE ha(-1) for GLY-IPA-1 and GLY-IPA-2 respectively in the absence of AMS. When AMS (20 g L(-1)) was added to the spray solution, the estimated IC50 values were 143, 76 and 60 g AE ha(-1) for GLY-IPA-1, GLY-IPA-2 and GLY-A respectively. Absorption of 14C-glyphosate into the third leaf of five- to six-leaf velvetleaf was three- to sixfold greater 72 h after treatment (HAT) when applied as GLY-A compared with GLY-IPA-1 and GLY-IPA-2 respectively in the absence of AMS. AMS (20 g L(-1)) increased absorption of 14C-glyphosate in all glyphosate formulations two- to threefold, but differences among the formulations remained. Approximately three- and sixfold more 14C-glyphosate applied as GLY-A had translocated out of the treated leaf compared with GLY-IPA-1 and GLY-IPA-2 respectively by 72 HAT. Adding AMS (20 g L(-1)) increased translocation of 14C-glyphosate out of the treated leaf approximately 2.5-fold for all three formulations. The increased efficacy of GLY-A versus GLY-IPA-1 and GLY-IPA-2 on velvetleaf is due to the greater rate of absorption and subsequent translocation of glyphosate out of the treated leaf. AMS increased the efficacy of all three formulations by increasing absorption and translocation of glyphosate in the plant.     

Foliar penetration and translocation of 2,4,5-T in blackberry (Rubus procerus P.J. Muell.)

Factors affecting the foliar penetration of 2,4,5-T and the translocation of this herbicide in blackberry (Rubus procerus P.J. Muell). are described. Foliar penetration studies showed that from 38% to 59% of the applied herbicide penetrated into leaves picked respectively in summer and autumn. Leaf uptake of 2,4,5-T was found to be temperature independent in young leaves (Q₁₀, = 1·3) and temperature dependent in older leaves (Q₁₀= 3·5). Some evidence is presented which suggests that this may be caused by the wax content of the cuticle. The herbicide translocated well into the root system of small plants, but probably in sublethal amounts. Penetration foliaire et migration du 2,4,5-T chez la mûre (Rubus procerus P. J. Muell.) L'auteur décrit les facteurs affectant la pénétration du 2,4,5-T et la migration de cet herbicide chez la mûre (Rubus procerus P.J. Muell.). Les recherches sur la pénétration foliaire ont montré que 38%à 59% de l'herbicide appliqué pénétrait dans les feuilles récoltées respectivement enete et en automne. II a été constaté que l'absorption foliaire du 2,4,5-T est indépendante de la température chez les jeunes feuilles (Q₁₀= 1,3) et dépendanle de la température dans les feuilles plus ãgées (Q₁₀= 3,5). Certains faits sont présentés qui suggérent que ce phénoméne peut être cause par la teneur en cire de la cuticule. l'herbicide migre aisément dans le systéme radiculaire des petites plantes, mais probable-ment en quantités sublétales. Blatlpenetration und Translokation von 2,4,5-T in der Brombeere (Rubus procerus P.J. Muell.) Es werden Faktoren beschrieben, die die Blattpenetration von 2,4,5-T und die Translokation dieses Herbizids in der Brombeere (Ruhus procerus P.J. Muell.) beeinflussen. Untersuchungen zur Blattpenetration ergaben, dass 38 bis 59% der angewandten Herbizidmenge in Blätter eindrangen die im Sommer bzw. im Herbst gepflückt wurden. Die Aufnahme von 2,4,5-T über das Blatt war bei jungen Blättern unabhängig von der Temperatur (Q₁₀= 1.3); bei älteren Blättern war sie temperaturabhängig (Q₁₀= 3.5). Es werden einige Befunde dargestellt, die darauf hinweisen, dass dies durch den Wachsgehalt der Kutikula verursacht sein könnte. Das Herbizid wurde gut in das Wurzelsystem kleiner Pflanzen transloziert, wahrscheinlich aber in sublethalen Mengen.     

Identification of cowpea (Vigna unguiculata) cultivars and lines immune to variants of blackeye cowpea mosaic potyvirus

Fifty-one cowpea ( Vigna unguiculata ) cultivars and lines were tested by mechanical inoculation against seven geographically and pathogenically diverse isolates of blackeye cowpea mosaic potyvirus (BICMV), to identify genetic resources with comprehensive BICMV resistance. Five genotypes, IT 80S 2049, Big Boy, Corona, Serido, and Tennessee Cream #8 were immune from all seven isolates, and an additional three genotypes, TVu-2657, TVu-2740, and TVu-3433, were immune from all isolates except PU-7B, an aberrant B1CMV isolate. The diversity among BICMV isolates was illustrated by the range of responses to inoculation among cowpea genotypes, many of which were either immune from or tolerant of individual B1CMV isolates.