Crop Rotation Controls Barley Root-Knot Nematode at Tulelake

barleyJ roo t-knot nematode at Tulelake

M. W. ALLEN * W. H. HART * KEN BAGHOTT

HE BARLEY ROOT-KNOT NEMATODE: the soil plots were inoculated with 2, 10, other root-knot nematode species in Cali- TMeloidogyne naasi Franklin, 1965, and 100 egg masses. A crop of barley fornia: (1) there is only one generation was found causing economic damage to was grown, harvested, and a second per year on barley; (2) eggs of this barley in the Klamath Basin near Tule- planting made. The effect of the nema- species require exposure to chilling be- lake, California, in 1964. The species tode upon the second crop of barley is fore they will hatch readily (maximum parasitizes barley in England and Wales shown in the photo of plant top growth. egg hatching occurs only after the eggs and has been reported from sugar beets The soil inoculated with 10 and 100 have been exposed to temperatures of in Belgium. It also occurs in Illinois, egg maiies produced significantly less about 40' F for a period of six weeks ICansas and Oregon. Known infestations top and root growth (1%level) than pots or more while eggs of other species hatch in California are in the Tulelakc area, receiving 2 egg maqses or no egg mass readily without exposure to low tempera- and a few locations in southern Cali- (CK) . The good growth of the 1)arley in tures) ; and (3) the host range of ill. fornia where the nematode has lieen pot MO (inoculated with water in which naasi differs from other California found on the roots of turf grasses. The the egg masses werp washed) indicates species of root-knot nematodes, its princi- infestation in the Tulelake area involves that mirro-organisms associated with the pal hosts arc in the grass family (Grami- several thousand acres that have been egg masses were not injurious. naceae), some of the common hosts of cropped almost continuously with bar- The barley root-knot nematode in the the root-knot nematodes M. incognita, ley since the land was reclaimed. Other Tulelake area differs hiologically from .$I. javanica, M. hapla, M. arenaria and crops sometimes grown in the infested HOST AND NON-HOST PLANTS OF BARLEY ROOT- M. than& are immune or highly re- area include alfalfa, oats, potato and KNOT NEMATODE IN THE TULELAKE AREA. qistant (see plant listing). wheat. Hosts Injury to barley plants is character- Alsike clover Control Barley (116 varieties) ized by invasion of infective larvae into Curley dock The use of conventional soil treatments Grasses (all species tested) the roots of young plants early in the Oats (21 varieties) with nematicides is not economical in growing season. Samples from infested Onion (very pocr host) harley culture. Information obtained in Rice (3 varieties) fields, taken early in May frequently Rye greenhouse and field tests concerning the have an average of 90,000 infected lar- Sorghum host range of the nematode was used as Sunflower vae per pint of sod. There is typical Wheof R guide in 1966, to pstablkh a series of formation of spindle-shaped galls, and Wild oats cropping sequences on an infested ex- roots may be killed when there is mas- Non-hosts perimental plot at Tulelake. Crops in- Alfalfa (African, Vernal, Ladok) sive infection (see photo). Heavily in- Australian winter peas cluded alfalfa, Australian winter peas, fected plants are stunted, become yellow Beans (commodore, black eye) barley, oats (Park), onions, and potatoes, Cantaloupe and may die. Surviving plants tend to Carrot in addition to fallow. The 1969 Iiarley remain stunted and do not produce nor- Celery Clover (Kenland, Ladino) yields resulting from several of the crop- mal heads. Crop losses are variable, but Corn ping sequences are shown in the tahle. Cotton (Acala 442) with high larval populations, losses may Cucumber Records show that growing non-host reach 50 to 75 per cent of the crop. Millet crops, or fallowing infested land for one Oats (Park, Cayuse, Curt, Indio, Kanota) Barley was planted in pots of sterilized Peas (early perfection) season prior to planting barley, will soil, and then inoculated with egg masses Potato (roots and tubers) greatly increase yields. It is important Safflower (P-4) of the barley root-knot nematode to show Squash that Park, Cayuse or other nematode- effects on plant growJh. In these tests Tomato (commercial) immune oat varieties be used if the crop

4 CALIFORNIA AGRICULTURE, JULY, 1970 Hanrichen boirley roots to left, not i nfested; to right, infested with barley root-knot nematode.

prior to barley is oats. Row crops, such as field soil, and in infested soil in the area before use as rotation crops to con- onions or potatoes, may he advantageous greenhouse, showed no evidence of tuber trol barley root-knot nematode. becausc of the opportunity for control- penetration by larvae and no mature fe- M. W. Allen is Professor, Department ling wild oats, which is ;L host of barley males were found in rootq. In greenhouse of Nematology; and W. H. Hart is Ex- root-knot nematode. Tests 10 and 11 (see tests, a very few females matured and tension Nematologist, University of Cal- table) indicate very good increases in produced eggs in onion roots hut no ma- ifornia, Davis. Ken Baghott is Farm harley yields that ran he obtained aftei ture females were found in the roots of Advisor, Modoc-Siskiyou counties. This one year of a highly resistant or immune field-grown onions. Immune oat varieties research was supported by a grant from row crop. Test 12, where potato was other than Park or Cayuse need further the U. S. Department of Interior, Bu- grown for two years preceding thc 1969 agronomic evaluation in the Tulelake reau of Reclamation. crop of barley, resulted in the best yield. Test 11 substantiated grower observa- tions that satisfactory harley yields can be obtained following a potato crop. In Hannchen barley top growth in pots inoculated with 100, 10, 2 and no egg masses (MO and CK) these tests onions and potatoes (as a crop of barley root-knot nematode. preccding barley) increased yield to higher lepels than did Park oats or lal- low, hut harlry yields were nearly dou- bled with the two latter treatments as compared with those obtained in continu- ous Larley crops (test 1). Potatoes grown in hravily infested

ROTATIONS AND RESULTING BARLEY YIELDS, 1969, TULELAKE, CALIFORNIA Test 1969 Yield No. 1966 1967 1968 Firlbecks Ill barley Crop Rotation Ibs/acre* 1 Barley Barley Barley 2732 a 2 Barley Oats Barley 3078 a b 3 Barley Onions Barley 3578 b 4 Oats Oats Barley 4155 c 5 Barley Barley Fallow 4155 c 6 Fallow Fallow Barley 4309 c 7 Barley Barley Oats 4463 c d 8 Onions Onions Barley 4540 c d 9 Potato Potato Barley 4579 c d 10 Barley Barley Onions 4886 'd 11 Barlev Barlev Potato 4925 d 12 Barlev Potato Potato 5541 e * Average of 4 replicates-yields with same letter not sig. diff. at 1%.

CALIFORNIA AGRICULTURE, JULY, 1970 5