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newly germinated seeds. Ovcr a temperaturę rangę ot U to 2l*C reproduction was best at 17 to 19*C 0 12 7 DERN, R. [Freeliving root-nematodes as pests of agricultural plants in Hessen-Nassau.] Freilebende Wurzelncmatoden ais Schadlinge an landwirtschaftlichen Kulturpflanzen in Hessen-Nassau. Gcsundc Pflanzcn (1977) 29, 287-289 [De] Pflanzenschutzamt Frankfurt am Main. GFR.

In Hessen-Nassau, German Federal Republic. damagc to cereals and maize, as well as to othcr agricultural crops, is caused in many fields by Pratylenchus neglectus and P. penctrans. Losses of between 20 and 34% were demonstrated in cereals, maize and fodder beet in fields infestcd with morę than 250 P. penctrans oc morę than 500 P. neglectus in 250 ml soil. Treatmcnts with nematicides such as Curaterr and Temik 10 G are profitable.

0 128 OGIGA, I. R.; ESTEY, R. H.    Penetratioo and

colonizatioo of Brassica rapa and Zea mays root tissues by Pratylenchus penctrans. Phytoprotcciion (1975) 56 (1) 23-30 (En, fr] Dep. of PI. Path., Macdonald Coli. of McGill Univ., Que., Canada.

Parasitism of Brassica rapa and Zea mays by Pratylenchus penctrans was studied on seedlings grown in soil or agar. Brownish neerotie lesions were formed on roots and many morę latera) roots were produced on parasitized plants than on control plants, particularly in soil-grown seedlings. Adults and juveniles migrated within a few min of inoculation towards the zonę of difTerentiation or to epidermal mptures caused by emerging lateral roots. The nematodes fed extema|)y on al) zones escept the root cap. Nemaiode migration within the root tissue was intracellular and although the process of penetration appeared to be mechanical it was often preceded by celi discolouration. Penetration of B. rapa occurred within 6 hours of inoculation and of Z. mays within 8 to 12 hours. unless penetration was through ruptures caused by emerging lateral roots when it was equa!!y rapid in both species. The endodermis of B. rapa was disrupted within 2 weeks of infeetton but ihat of Z. mays was not afTected. Mass invasion of B. rjpj sometimcs occurred causing lesions open to the stele. Histochemical (ests showed the presence of phcnols in the host roots.

0120 BEHR1NGER, P. [Maize cultitation and cereal nematodes. Ezperience in Barana.} Maisanbau und Getreidenematoden. ErfahrungsbericHt aus Bayem. Mais (1978) No. 1, 18, 27*28 (De) Bayeriscbe Landesanstalt fur Bodenkultur und Pflanzenbau, Neuburg a.d. Donau, GFR.

Heterodera avenae is widespread in Bavaria, German Federal Republic. and is present in 78% of fields. A generał account of the nematode on cereals is given and the use of resistant varieties is recommended as being the only way of overcoming the disease. The nematode pathotypes A, B, C and D are present, sometimes in mixed populations, and possibly also pathotypes E and F in the hill country of upper/lower Bararia. Maize is in a different category frora that of othcr cereals because nematode larrae enter the roots but may not maturę. Crop yields may be reduced but the nematode population is also reduced. The nematode-reducing influence of maize was demonstrated in an experiraent started in 1967 where, after 10 years of maize monoculture, the heavy infestatioo of cyst nematodes was also completely destroyed, while in an area growing summer wheat the infestation remained very high. In Bavaria, where frequent maize crops are combined with widespread growth of wmter wheat. infestations of cereal cyst nematodes remain slight.

0 1 30 0RR, C.C.,    1967. "Obseryations on

cotton root-knot nematode in grain sorghum in West Texas." PI. Dla. Reptr, 51 (1), 29.

Meloidogyne incogntta acrlta was found associated with reduced growth and yield of grain sorghum in Teaas, U.S.A.

0 13 1 RhoadES, H. L. Eraluation of nematicides and methods of their application for control of nematodes od field corn. Nematropica (1979) 9 (l) 43-47 [En, es) Agric. Res. &. Education Center, P.O. Box 909, Sanford, FL 32771, USA.

In a 2 year field experiment maize (Zea mays) yields were inereased by application of various fumigant and non-volatile nematicides by an average of 28% in 1977 and 58% in 1978. Yield inerease was corTelated to a decrease in numbers of BeJonolaimus longicaudatus. DBCP and EDB also gave good control of B. longicaudatus and DBCP controlled    Hoplolaimus    galeatus. Stubby    nematodes

(Paratrichodorus christiei) were controlled by terbufos, phenamiphos and CG A-12223. .Application of phenamiphos, carbofuran, aldicarb and oxamy) in a 38 cm band incorporaled by rotary wheels just prior to planting was morę efTect»ve than application in a 25 cm band in front of the press wheel or in the seed furrow with the planter.

*0132 Willis. C. B.; Thompson. L. S. Effects of pdenamipbos, metbyt bromide, and fallowing on Pratylenchus penctrans, yield of Medicago satira, and Fu sari u m infections. Journal of Sematology (1979) 11 (3) 265-269 [En] Agric. Canada, Res. Station, P.O. Box 1210, Charlottetown, Prince Edward Island. Canada CIA 7MS.

In a field study the effects of phenamiphos (22.4 kg a.i./ ha), methyl bromide (488 kg/ba) and Gllowing on the numbers of Pratylenchus penetrans, luceme yields and the incidence of Fusarium spp. were measured. In the Ist year plota were left fallow or sown to red clover and in the 2nd year luceme was planted and Chemical treatment applied. Luceme was croppcd for a further 3 years. Fallowing imtially controlled the nematodea but at the end of the 2nd growing season populations were as dense as in plots wbich had grown a susceptible crop. Yields were inereased only in the Ist year after fallowing and Fusarium was not reduced. Phenamiphos treatment reduced nematode numbers, inereased forage yields in 2 of the 4 years and reduced Fusarium infection of taproots. The best control of P. penetrans and Fusarium infection was obtained following methyl bromide treatment and luceme yields were inereased in ali 4 years.

0 13 3 CasparY. W. [Invesrigations on the epidemiology of and injury caused by Ditylencbus dipsaci (Kuba 1857) Filipjer, 1936 on maize.] Untersuchungen zur Epidemiologie und Schadwirkung von Ditylencbus dipsaci (Kiihn 1857) Filipjev 1936 an Mais. Thesis, Universitat Bonn, German Federal Republic. (1976) 116 pp. [De] Rheinische Friedrich-Wilhelms Univ., Bonn, GFR.

Glasshouse and field experiments were done to investigate the epidemiology and disease caused by Ditylenchus dipsaci infecting maize. Plant invasion was influenced mainly by the stage of development of the host, soil moisture and environmental factors. Attack diminished with inereasing age of the seedling. Maximura attack and most damage occurred at over 50% water saturation and I5*C soil temperaturę. At 20 to 25'C invasion was less, shoot growth was inereased and root development reduced, as compared with uninoculated control plants. DifTereot maize varieties were attacked to different degrees but no resistance was observed. Fresh weight reduction in comparable plants varied between 0 and 100% with a tnean of about 15%. A similarly wide variation occurred in plant infection but there was a lack of correlation between infection and damage. The non-uniform bchaviour of the same population of D. dipsaci on maize and other plants was based on the genetic heterogeneily of the parasite and host.. The identity of the race of the 2 beet populations of the nematode could not be clearly determined by host-range tests. The use of raorphological criteria for race separation is impossible because the host plant and temperaturę can cause modifications. Maize was also attacked by an isoiate froir tobacco. Ali motiie stages of the nematode could attack muizt but predominantly 4th stage Iarvae. Only rarely did morę than 20% of the inoculum invade, usually less than 1%. Shoots as well as roots were penetrated and reproduction 105 took place in them. The unusual behaviour of the nematode