Vigour control, an integrated approach to cane, pest and disease management in red raspberry (Rubus idaeus)

The first flush of young canes of red raspberry (Rubus idaeus) was removed at different dates in spring, using the contact herbicide dinoseb. In comparison with untreated plots, cane removal increased fruit yield, controlled excessive cane vigour, and improved the health status of vegetative canes in a plantation infested by raspberry cane midge (Resseliella theobaldi). At the end of the growing season vegetative canes on treated plots were shorter and thinner, and sustained less physical injury than those on untreated plots. Access to the fruit at harvest was also improved. Reduced competition between fruiting and vegetative canes increased yield in the year of treatment by an average of 35%. Yield was not affected by date of cane removal, but growth of replacement cane was reduced below optimum when first flush cane was removed after mid-May. The later the canes were removed, the less was the incidence of pest and diseases. Cankers and lobate vascular lesions (‘patches’) resulting, respectively, from the feeding of first and second generation midge larvae (with associated fungi) affected fewer canes in treated than in untreated plots. Significantly fewer live larvae of R. theobaldi were recovered in the following winter from soil in plots treated on or after 11 May than from untreated plots. The main effect of vigour control on R. theobaldi and midge blight was that replacement canes provided fewer egg-laying sites (natural splits) than did the first flush canes on untreated plots. The incidence of spreading vascular lesions (‘stripes’) attributed to Leptosphaeria coniothyrium infecting either physical wounds (cane blight) or midge feeding wounds (midge blight) was substantially less in treated than untreated plots. Cane botrytis (Botrytis cinerea) and spur blight (Didymella applanata) were also less common in treated plots. Interactions between vigour control and pest and disease incidence are discussed in relation to the efficient management of cv. Glen Clova in eastern Scotland.     

Effect of machine-harvester wounds and Leptosphaeria coniothyrium on yield of red raspberry

When wounds on raspberry canes caused by machine harvesting in the previous year were infected by Leptosphaeria coniothyrium the potential yield per cane was reduced by 45% compared with that of uninfected hand harvested canes. However, the corresponding reduction per plot was less (c. 25%) because the yield of wounded but uninfected canes was not reduced and some canes were not wounded. The advantages and disadvantages of recording potential yield per cane are discussed.     

The effect of sprays of thiophanate–methyl on cane diseases and yield in red raspberry, with particular reference to cane blight (Leptosphaeria coniothyrium)

Spur blight (Didymella applanata), cane botrytis (Botrytis cinerea) and cane blight (Leptosphaeria coniothyrium) were studied in two consecutive seasons in unsprayed raspberries and in plots sprayed with thiophanate-methyl in the first season alone, (a) twice pre-harvest, (b) twice post-harvest, or (c) twice pre- plus twice post-harvest. Pre-harvest, but not post-harvest sprays, gave moderate control of both spur blight and cane botrytis; both diseases occurred mainly on the lower halves of canes, the latter being the less common. Cane blight occurred at the base of canes where they were wounded by old cane stubs. In the first year it was severe; 37% of canes died before harvest in the unsprayed plots. The three spray programmes all decreased cane death due to cane blight and they all increased yield by c. 45% even in those plots sprayed post-harvest where spur blight was severe and not controlled. Clearly this last disease, despite its high incidence, had no effect on potential yield in this experiment. In the second year cane blight was common but less severe and the incidence of its lesions was reduced similarly by all programmes, but only 4% of canes died in control plots. Analysis of the potential yield and the sizes of lesions caused by L. coniothyrium in canes inoculated at fortnightly intervals in the previous year showed that potential yield loss occurred only when lesions girdled canes. A bimodal distribution in the lesion sizes, measured by length or girdling, indicated some endogenous control of lesion development which might explain the marked differences in the effect of cane blight on potential yield in two seasons.     

Cane blight (Leptosphaeria coniothyrium) in mechanically harvested red raspberry (Rubus idaeus)

Leptosphaeria coniothyrium, the cane blight pathogen, was the fungus most commonly isolated from vascular lesions developing from mechanical harvester wounds on first-year red raspberry canes. When inoculated to scalpel wounds, it induced similar lesions which were later associated with bud failure and cane death as were infected wounds on machine damaged canes. Cane resistance increased from May until August, inoculations later than July inducing only small lesions and rarely causing bud failure.     

A technique for scoring midge blight of red raspberry, a disease complex caused by Resseliella theobaldi and associated fungi

A scoring technique is described for assessing midge blight using maps representing vascular lesions beneath periderm damaged by second generation larvae of Resseliella theobaldi . Individual canes were scored and some components of yield examined. Yield was not affected until lesions covered more than 20% of the stele surface at the base of canes. Midge blight scores increased with cane girth, probably because splitting of the cortex was most extensive in stout canes.     

Effects of straddle-harvester design on cane blight (Leptosphaeria coniothyrium) of red raspberry

A new fruit catching device developed for raspberry straddle harvesters to reduce wounding of young canes and their consequent infection by Leptosphaeria coniothyrium was tested. During picking the young canes were contacted only by the foam rubber on a pair of belts which moved backwards along the harvester at the same speed that the machine advanced. The incidence of canes with cane blight lesions in 1981 was 18% following the use of the new device in 1980, and 79% following the use of a conventional commercial harvester equipped with overlapping metal fruit-catching plates. In comparison with the latter plates, the new device avoided wounding the cane surface directly: when the belt marks on these canes were inoculated with mycelium, however, the disease incidence was 77%. The new device caused wounds in 1980 by ripping leaves from nodes. In comparison with the commercial harvester the new device led to smaller lesions in 1981 and a lower percentage of canes dead above the fruit-catching zone. A modified new catching device tested in 1982 made barely detectable pressure marks on the young canes without bruising them. Only 6·6% of these canes developed vascular lesions after inoculation, an incidence similar to that for unwounded control canes (2·5%). The modified new device is advised for regions prone to cane blight where the cropping system has young and fruiting canes growing together.     

Disease measurement in a study of apple scab epidemics

The growth and yield increases in red raspberry which followed the repeated application of benomyl were not due to the suppression of pests. Benomyl had little effect on numbers of aphids and nematodes which, anyway, were insufficiently abundant to cause damage. Benomyl did, however, decrease the earthworm population. In the following years, when benomyl was no longer applied, significantly more canes died from midge blight in the plots treated most frequently with benomyl than in the untreated. This was probably a consequence of increased infestation by larvae of the raspberry cane midge (Resseliella theobaldi) in the benomyl-treated plots because benomyl increased the extent of cane splitting and hence the number of egg-laying sites for cane midge.     

Factors affecting the development of cane blight (Leptosphaeria coniothyrium) on red raspberries in Washington, Scotland and Germany

The effects of cultivar, virulence of isolates of Leptosphaeria coniothyrium, cane maturation and wound healing were examined in a series of inoculation experiments carried out over a 3–yr period in three countries in an attempt to explain why cane blight has caused serious yield losses in machine-harvested red raspberries in Europe, but not in the Pacific Northwest of America. Three isolates of L. coniothyrium from Puyallup (USA), Dundee (UK) and Dossenheim (FRG) were pathogenic on the three test cultivars Willamette, Malling Jewel and Glen Isla in all the experiments. Isolates and cultivars differed for aggressiveness and susceptibility respectively but their ranking was dependent on the test conditions and the differences were small and unlikely to explain the differences in incidence and severity of cane blight in raspberry fields in Scotland and the Pacific Northwest. Conditions at Dossenheim were most favorable for lesion development. At all sites, canes inoculated in late summer produced shorter lesions than those inoculated earlier. A delay between wounding and inoculation produced shorter lesions than simultaneous wounding and inoculation.     

Resistance to raspberry cane midge (Resseliella theobaldi) and its association with wound periderm in Rubus crataegifolius and its red raspberry derivatives

Rubus parviflorus, R. odoratus and F₂ plants from the cross R. crataegifolius x R. idaeus were resistant to the raspberry cane midge (Resseliella theobaldi) when exposed to the pest in an insectary or in the field. Histological studies of R. crataegifolius and one of its hybrids with R. idaeus showed that resistance was associated with a wound periderm of suberised and lignified cells. These cells were formed from the primary cortex and phelloid cells of the polyderm as a rapid response to the occurrence of natural splits and wounds which are the oviposition sites of R. theobaldi. In the hybrid, new tissues from this wound periderm prevented the peeling of the mature primary cortex, thereby precluding serious midge attack, and resulted in a reticulate appearance on the cane surface, a distinctive cane feature useful for identifying resistant segregates.     

Further studies on resistance to Leptosphaeria coniothyrium in the red raspberry and related species

Rubus pileatus and its F₁ hybrids with raspberry (R. idaeus) were resistant to cane blight (Leptosphaeriu conioth-yriurn), but little resistance was obtained in subsequent backcross generations apart from a hybrid identified in the second backcross. Two hybrids from backcrossing R. coreanus to raspberry also showed resistance. R. pileatus and its F, hybrids produced hard growth, unlike that of raspberries, which may have been associated with a form of resistance that could not easily be transferred to commercial raspberry cultivars. Some of the genotypes used as parents showed intermediate levels of resistance and it is possible that the highly resistant genotype identified in the second backcross arose from a recombination of genes for resistance. Plants with pubescent canes (gene H) were up to 20% more resistant to mycelial inoculation than those with non-pubescent canes (gene h), and the percentage of machine-harvester inflicted wounds with disease symptoms that resulted from natural infection was also less in genotypes with pubescent canes. Many genotypes with intermediate levels of resistance suffered only limited damage from mycelial inoculation and so there are good prospects for breeding cultivars with an effective resistance, despite the limited value of R. pileatus as a donor species.     

Comparison of cross inoculation potential of South African avocado and mango isolates of Colletotrichum gloeosporioides

Three hundred and eighteen Colletotrichum gloeosporioides isolates from stem-end rot and anthracnose infected avocados as well as from stem-end rot/anthracnose and soft brown rot on mango, were compared using fruit inoculations. Isolates could be categorised according to lesion size and both avocado and mango isolates produced larger lesions when inoculated on their own hosts. Cross-inoculation potential of these isolates was also compared on strawberries, peppers, guavas, papayas and citrus. All isolates produced lesions on all hosts except citrus. Factors such as area of origin and symptom type from which original isolations were made, could not be correlated with lesion development on these hosts.     

套袋苹果褐点病菌分类鉴定及致病性

2011和2012年山东栖霞、蓬莱、沂源等地套袋苹果果实出现了一种红褐色病斑。从病斑上分离获得两株枝顶孢属Acremonium真菌,其中一株产生头状排列的分生孢子,另一株产生链状排列的分生孢子。2个菌株都能从伤口侵染近成熟期的苹果果实,导致果肉细胞坏死,表面凹陷,形成红褐色坏死斑。2个菌株都不能侵染无伤果实。2个菌株的ITS、β-微管蛋白基因、核糖体大亚基（nucLSU）和小亚基（nucSSU）的DNA序列完全相同。依椐两个菌株的ITS和nucLSU的DNA序列和形态特征,将2个菌株鉴定为菌核生枝顶孢Acremonium sclerotigenum。A. sclerotigenum是一种机会真菌,条件适宜时可侵染套袋的苹果果实,导致褐色坏死病斑,称之为枝顶孢褐点病。     

The effect of cane management techniques on raspberry yellow rust (Phragmidium rubi-idaei)

The effects of various cane removal treatments on the epidemiology of Phragmidium rubi-idaei were studied in four experiments in infected raspberry plantations in Wales and Scotland. In 1981, removal of 15 cm high young canes either by cutting or by spraying dinoseb-in-oil reduced infection of a second flush of canes (replacement canes) compared to that of the first flush of canes on untreated plots of cv. Mailing Delight in Wales and of cv. Glen Clova in Scotland. In 1982, removal of 20 cm high young canes reduced infection of cv. Mailing Delight in Wales but in Scotland only removal of 60 cm high canes by cutting reduced infection of replacement canes. Removal of all fruiting canes and old cane stubs reduced rust infection of young canes, but removal of successive flushes of replacement canes did not reduce infection of lateral shoots on the fruiting canes. Dinoseb-in-oil applied to the bases of fruiting canes before emergence of young canes had no effect on infection of young canes in Wales or Scotland. The production of basidiospores was inhibited in vitro by dinoseb-in-oil at concentrations over 1.0 μg a.i./ml.     

Morphological assessment of water stressed sugarcane: A comparison of waterlogged and drought affected crop

Abiotic stress is recurrent occurring problem for sugarcane crop in terms of hindrance in achieving good and high production. In India, drought coverage is 2.97 lakh ha while 2.5 lakh ha under coverage of waterlogging which is one of the reasons behind low cane production and productivity due to alteration in metabolism, growth and development of the plant either in direct or indirect way. Therefore, we investigated the comparison of morphological losses in drought and waterlogging sugarcanes. Morphological parameters assessed were leaf length, leaf width, leaf area, stalk diameter, cane height, cane weight, internodes number and average internodal length. Also, total root weight, dry matter production of stalk, leaves and roots were observed. Results showed that leaf length was marginally increased in drought canes but it was not so in case of waterlogged canes. Besides, there was decrease in total root weight of sugarcane affected by drought by 16.99% while there was increase by 10.06% in waterlogging affected canes in comparison to normal grown canes. In cane height and stalk diameter, decrease by 18.28%, 7.52%, respectively, in drought and 11.41%, marginal decrease, respectively, in waterlogged affected canes as compared to normally grown canes. Average internodal length was also found to increase in both drought as well as waterlogged canes by 39.02% and 36.60%, respectively, in comparison to normal grown canes. Number of internodes was decreased more in drought affected canes than in waterlogged canes. This study concluded that there are higher morphological losses in sugarcane in drought condition than in waterlogging conditions with respect to normal grown canes.     

Interaction of endodormancy and paradormancy in raspberry (Rubus idaeus L.)

Bud break in protected Northern European raspberry crops is often poor and uneven with many of the sub-apical buds remaining in a dormant state. In order to improve bud break and therefore yields, the mechanism controlling bud dormancy must be determined. Canes of the biennial cultivar ‘Glen Moy’ were forced as isolated single nodes, trisections, or as intact canes after different lengths of cold storage chill unit (CU) accumulation in order to determine whether the buds were in an endodormant or paradormant state. The results showed that buds on the lower parts of the intact canes remained in a dormant state long after buds from higher up the intact cane and also the single nodes from all parts of the cane had emerged from the deepest phase of endodormancy. This would imply that these buds were being held in a paradormant state until large amounts of chilling units (>1000 CU) had been accumulated. The trisected cane portions revealed almost no significant differences in bud break levels throughout the experiment when compared with the single nodes. This suggests that removal of the apical part of the cane would be effective in improving bud break by reducing the paradormant condition. A period of secondary dormancy was also observed in the intact canes which may also exacerbate the poor bud break observed in protected crops. This was not seen in the single nodes or the trisected canes which indicates that treatments which reduce paradormancy may also minimise the risk of secondary dormancy. By identifying the phase of bud dormancy which causes poor bud break, attention can now be focused on methods which overcome paradormancy in protected crops. Such methods might include tipping (removal of the cane apex), horizontal training methods, more efficient chilling methods, and chemical treatments.     

Structure of the Chlamydomonas agglutinin and related flagellar surface proteins in vitro and in situ

Using the quick-freeze, deep-etch technique, we compare the structure of the cane-shaped plus and minus sexual agglutinin molecules purified from gametes of Chlamydomonas reinhardi. We also describe the structure of three additional gamete-specific fibrillar molecules, called short canes, loops, and crescents, which are structurally related to the agglutinins. Four non-agglutinating mutant strains are found to produce the three latter fibrils but not canes, supporting our identification of the cane-shaped molecule as the agglutinin. The heads of the plus and minus canes are shown to differ in morphology. Moreover, two treatments that inactivate the plus agglutinin in vitro--thermolysin digestion and disulfide reduction/alkylation--bring about detectable structural changes only in the head domain of the cane, suggesting that the head may play an indispensible role in affecting gametic recognition/adhesion. We also present quick-freeze, deep-etch images of the flagellar surfaces of gametic, vegetative, and mutant cells of Chlamydomonas reinhardi. The gametic flagella are shown to carry the canes, short canes, loops, and crescents present in in vitro preparations. The cane and crescent proteins self-associate on the flagellar surface into stout fibers of uniform caliber, and they align along the longitudinal axis of the flagellum. The short canes and loops co-purify with flagella but, in the presence of mica, dissociate so that they lie to the sides of the flagella. The agglutinin canes of both mating types are oriented with their hooks at the membrane surface and their heads directed outward, where they are positioned to participate in the initial events of sexual agglutination.     

Penetration of the Periderm of Red Raspberry Canes by Leptosphaeria coniothyrium

Umwounded raspberry canes were inoculated with Leptosphaeria coniothyrium. After penetration of the epidermis the fungus invaded the cortex readily. The accumulation of mycelium in this tissue lead to a partial digestion of the middle lamellae of the outermost cork layer within the polyderm. The fungus penetrated this single cell barrier through the openings between the separated cells and colonized the phelloid tissue between the first and second cork layer. After vigorous growth in this non-suberized tissue the fungus penetrated the second cork barrier in the same way as the first layer. This mode of penetration was repeated until the fungus had spread beyond the periderm and into the vascular tissues. The invasion process occurred rather slowly and was enhanced by weakening of the canes by defoliation at the time of inoculation.     

Resistance to Leptosphaeria coniothyrium in the red raspberry and some related species

Useful resistance to Leptosphaeria coniothyrium was found in the red raspberry cv. Latham, but its effectiveness was affected by the stage of growth reached by the canes when they were inoculated and by the kind of inoculum used: it was effective when field-grown canes were inoculated in mid-August but less so when they were inoculated in early July, and more effective against a spore inoculum than against a mycelial one. Resistance was inherited as a dominant multigenic character, but there were interactions between parents and two very favourable combinations were found.
The species Rubus pileatus, R. mesogaeus, R. coreanus and R. lasiocarpus showed resistance when inoculated in pot experiments, but F₁ hybrids obtained by crossing them with the raspberry were largely susceptible. The problems of using these resistance sources in breeding are discussed.     

Interrelationship between the raspberry cane midge, Resseliella theobaldi (Diptera: Cecidomyiidae) and its parasitoid, Aprostocetus epicharmus (Hymenoptera: Eulophidae)

The raspberry cane midge Resseliella theobaldi (Barnes) is one of the most important pests of cultivated red raspberry Rubus idaeus L. throughout Europe. For the last 50 years several studies have been made on the biology, life cycle and control of the pest. Some data can also be found on its natural enemies, but among these species only the chalcidoid Tetrastichus inunctus Nees turned out to be important in controlling raspberry cane midge populations. However, this species name is now ambiguous as the type is lost. In the present study, Aprostocetus epicharmus Walker was the chalcidoid species that parasitized the larvae of the raspberry cane midge, and its biology seems to be very similar to that of T. inunctus. It is therefore probable that the eulophid species earlier referred to as T. inunctus in the literature is A. epicharmus. Besides discussing this problem, particular consideration and detailed data are given on the biology and life cycle of A. epicharmus in relation to R. theobaldi. Different factors having effect on the population dynamics of both species are also discussed as results of a survey on several red raspberry cultivars, carried out in Hungary between 2002 and 2005.     

DRY-ROT DISEASE OF THE POTATO

Inoculation of wounded tubers at intervals throughout the storage season showed that, after harvesting, resistance to infection by F. avenaceum was maintained for a longer period than resistance to F. caeruleum , although eventually the tubers became equally susceptible to both fungi. Tubers were less readily infected through clean-cut than through scarified wounds. Resistance to infection was greater when an interval elapsed between wounding and inoculation than when the wound was inoculated immediately; this was related to an increase in the intrinsic ability of the cells near the wound to resist infection rather than to suberization of the wounded surface or wound periderm formation.
Histological studies showed that F. caeruleum grew through the intercellular spaces and that the adjacent host cells remained alive, often for considerable periods, whereas F. avenaceum killed and penetrated the cells with which it came into contact. Restriction of incipient or established lesions caused by F. caeruleum and of incipent lesions caused by F. avenaceum was associated with suberin deposition on the host cell walls and in the intercellular spaces; in established lesions caused by F. avenaceum , restriction was attributed to an increase in the intrinsic resistance of the adjacent host cells, similar to that found near a wounded surface.