Three preplant soil fumigation treatments were applied on 5 Apr. 1993 to a nursery site that had not been planted previously to strawberries (Fragaria ×ananassa Duch.): 1) a mixture of 67 methyl bromide: 33 chloropicrin (CP) (by weight, 392 kg·ha–1) (MBCP); 2) 140 kg CP/ha; and 3) nonfumigation (NF). On 26 Apr., cold-stored `Chandler' and `Selva' strawberry plants of registered stock were established in each treatment. Soil and root/crown disease symptoms were absent in all treatments during the course of the study. In October, runner plants were machine-harvested and graded to commercial standards. The cultivars produced a similar number of runners per mother plant. Fumigation with MBCP, CP, and NF resulted in 18.56, 15.75, and 7.89 runners per mother plant, respectively. For `Selva', runner root and crown dry weights were similar for the MBCP and CP treatments, but NF resulted in significant reductions compared to the other two treatments. For `Chandler', fumigation with CP resulted in reduced root dry weight, and NF resulted in reduced crown and root dry weights compared to fumigation with MBCP. The results demonstrate the marked decreases in strawberry runner production and runner size that can occur in the absence of preplant soil fumigation, even on new strawberry ground. Also, small, but significant, reductions in runner production and runner size may occur with CP applied at a rate of 140 kg·ha–1 compared to standard fumigation with MBCP. Chemical name used: trichloronitromethane (chloropicrin).
Kirk D. Larson and Douglas V. Shaw
Mary C. Stevens, Rui Yang, and Joshua H. Freeman
nature of soil fumigants, effects on soil microbes are typically observed, including those responsible for transformation of nitrogen. Soil fumigation often results in an increase of NH 4 + released from the killed microbial biomass and can remain in an
Kirk D. Larson
Replant soil fumigation with mixtures of methyl bromide (MeBr) and chloropicrin (trichloronitromethane) is a standard practice for pest and disease control in fruit crop nurseries in California. The proposed phase-out of MeBr by the year 2001 requires that alternative soil sterilants be studied for nursery use. Therefore, on 5 April, 1993, three preplant soil treatments were applied to new strawberry ground: 1) MeBr/chloropicrin (67:33) at 392 kg/ha: 2) chloropicrin, a possible MeBr substitute. at 140 kg/ha: and 3) nonfumigation. The experimental design was a RCB: there were two plots (each 10′ × 15′) for each of two cultivars (`Chandler' and `Selva') for the 3 soil treatments in each of 3 blocks. Mother plants were planted 26 April, and plots were machine-harvested in October, 1993. All plants from each plot were uniformly graded, after which mean stolon yield per mother plant, mean crown diameters, and crown and root dry wts were determined. Cultivar effects and cultivar × treatment interactions were not observed, so data for the two cultivars were pooled. Stolon production per mother plant was greatest for trt 1 (18.56 stolons), intermediate for trt 2 (15.75 stolons), and least form 3 (7.89 stolons). For trt 3, crown dieters. and crown and root dry wts were reduced relative to those of trts 1 or 2. Stolons from all trts were planted in a fruit production field on 13 October, 1993. After two months, canopy diameters were greatest for plants from trt 1 (27.1 cm), intermediate for plants from trt 2 (26.2 cm) and least for plants from trt 3 (24.9 cm). The results indicate that, compared to standard soil fumigation with MeBr/chloropicrin. small, but significant, reductions in runner production and plant vigor can be expected following nursery soil fumigation with intermediate rates of chloropicrin.
Michelle M. Leinfelder, Ian A. Merwin, Gennaro Fazio, and Terence Robinson*
We are testing control tactics for apple replant disease (ARD) complex, a worldwide problem for fruit growers that is attributed to various biotic and abiotic soil factors. In Nov. 2001, “Empire” apple trees on five rootstocks (M.26, M.7, G.16, CG.6210, and G.30) were planted into four preplant soil treatments—commercial compost at 492 kg/ha soil-incorporated and 492 kg·ha-1 surface-applied), soil fumigation with Telone C-17 (400 L·ha-1 of 1,3-dichloropropene + chloropicrin injected at 30 cm depth five weeks prior to replanting), compost plus fumigant combination, and untreated controls—at an old orchard site in Ithaca, N.Y. Trees were replanted in rows perpendicular to, and either in or out of, previous orchard rows. Irrigation was applied as needed, and N-P-K fertilizer was applied in 2001 to all non-compost treatments to compensate for nutrients in the compost treatment. After two growing seasons, the rootstock factor has contributed most to tree-growth differences. CG.6210 rootstock supported greater growth in trunk diameter, central leader height, and lateral shoot growth (P < 0.05), regardless of preplant soil treatments and replant position. Trees on M.26 grew least over a two year period. Replant growth was greater in old grass lanes than in old tree rows, despite higher root-lesion nematode populations in previous grass lanes. Growth responses to preplant soil fumigation were negligible. Preplant compost did not increase tree growth during year one, but did increase lateral branch growth in year two. Results thus far suggest that replanting apple trees out of the old tree-row locations, and using ARD tolerant rootstocks such as CG.6210, may be more effective than soil fumigation for control of ARD in some old orchard sites.
David G. Himelrick, Floyd M. Woods, and W.A. Dozier Jr.
The use of soil solarization on 20-cm raised beds 30, 60, and 90 days prior to fall planting of `Chandler' strawberries was compared with soil fumigation with 269 kg·ha–1 98/2 methylbromide/choropicrin and with 562 liters·ha–1 metam-sodium (Busan). The clear plastic mulch was painted with white latex paint prior to planting on 15 Oct. Methylbromide/choropicrin treatment gave the best yields, followed by the metam-sodium treatment. Soil solarization on raised beds was complicated by weed growth on the top edges and sides of the bed. Soil solarization is a useful alternative for flat bed culture, but is practically limited on raised beds due to insufficient weed control.
Renee M. Harber, Andrew P. Nyczepir, Umedi L. Yadava, and Ronald R. Sharpe
The effects of rootstock, pruning, and preplant soil fumigation on floral bud dormancy status and shoot cold hardiness of `Redhaven' peach [Prunus persica (L.) Batsch] trees were monitored. Dormancy status, expressed as percent floral budbreak, was significantly affected by rootstock and pruning, although differences were small. In late January, significant interactions occurred between rootstock and pruning treatments, as well as between pruning and soil treatments. Pruning of trees on Lovell rootstock resulted in significantly lower budbreak as compared to trees on Nemaguard and unpruned trees on Lovell. Also, for trees pruned in December, higher budbreak was associated with those growing in fumigated vs. nonfumigated soil. Treatment effects on dormancy status did not correspond with treatment effects on hardiness. In fact, differences in hardiness were minimal and probably not biologically meaningful.
Kirk D. Larson, Douglas V. Shaw, and Jerry Sterrett
Three preplant soil fumigation treatments were applied to a strawberry fruit production field in Summer 1993: 1) a mixture of 67 methyl bromide: 33 chloropicrin (wt/wt, 392 kg·ha–1) (MBC); 2) chloropicrin (trichloronitromethane, 336 kg·ha–1) followed by metam sodium (935 liters·ha–1) CMS); and 3) nonfumigation (NF). Bare-rooted `Camarosa' strawberry plants were established in each treatment on 1 Nov. in annual hill culture. Plant mortality was <1%; thus, differences in growth and productivity among treatments were due to sublethal effects of competitive soil organisms. Fruit yields were recorded weekly from 14 Jan. to 23 May 1994. For the NF treatment, early season (January–March), late season (April–May), and total yields were 86%, 69%, and 72%, respectively, of those of the MBC treatment. Early season yields were greatest for the MBC treatment, but late and total yields were greatest for the CMS treatment. From Jan. through May 1994, 20 plants were destructively harvested from each treatment at about monthly intervals for determination of leaf (LDW), crown (CDW), and root dry weight (RDW). For a given date, LDW, CDW, and RDW of plants in the MBC and CMS treatments were greater than those of the NF plants. From January to March, plants in the NF treatment allocated a proportionally greater amount of dry matter to roots, and proportionally less dry matter to crowns and leaves than fumigated plants. In April and May, root: shoot ratios were similar for all three treatments. These data demonstrate the marked influence of soil fumigation treatment on yield and dry matter partitioning of strawberry, and suggest that combinations of chloropicrin and metam sodium may be a viable, albeit expensive, alternative to fumigation with methyl bromide.
Kirk D. Larson and Douglas V. Shaw
Bare-rooted `Camarosa' strawberry runner plants were established in a fruit production field on 1 Nov. 1993 using annual hill culture and two preplant soil fumigation treatments: 1) a mixture of 2 methyl bromide: 1 chloropicrin (wt: wt, 392 kg·ha-1) injected into the soil before forming raised planting beds (MBC); or 2) nonfumigation (NF). At about 33-day intervals between mid-January and the end of May, 20 plants were destructively sampled from each treatment to determine leaf dry mass (LDM), crown dry mass (CDM), root dry mass (RDM), and shoot: root dry mass (SRDM) ratios. Plant mortality was <0.2% throughout the study and did not differ with soil treatment. Regardless of sampling date, LDM, CDM, and RDM were greater for MBC plants than for NF plants, although treatment differences were not always significant. During the first 143 days, NF plants allocated a greater proportion of dry matter to roots than to shoots compared to MBC plants, indicating that roots are a stronger sink for photoassimilate in nonfumigated than in fumigated soils. However, there was no difference between treatments in SRDM by the end of the study. Fruit yield and a 10-fruit weight were determined at weekly intervals from mid-January until 23 May 1994. Yield and mean fruit weight of NF plants were 72% and 90%, respectively, of that of MBC plants. For both treatments, about one-half of total fruit production occurred between 144 and 174 days after planting (late March to late April). During that same period, rates of dry matter accumulation in leaf, crown, and root tissues decreased for plants in both treatments, but greatest reductions occurred in NF plants. Chemical name used: trichloronitromethane (chloropicrin).
Yan Xu, Rachael E. Goodhue, James A. Chalfant, Thomas Miller, and Steven A. Fennimore
, identifying technically and economically viable alternatives for preplant soil fumigation in California strawberry production is an urgent task for researchers. Strawberries are an economically important crop in California. In 2012, the total value of
Mark Hoffmann, Husein A. Ajwa, Becky B. Westerdahl, Steven T. Koike, Mike Stanghellini, Cheryl Wilen, and Steven A. Fennimore
Intensive fruit, ornamental, and vegetable production systems in the United States and elsewhere in the world rely on preplant soil fumigation to control soil-borne pathogens, pests, and weeds. These include strawberry ( Fragaria × ananassa ) and