DM3-Monfort.Pdf (430.4Kb)
Total Page:16
File Type:pdf, Size:1020Kb
2007 Extension Research Report Disease Management EVALUATION OF BRASSICA COVER CROPS FOR CONTROL OF SOILBORNE PEST AND DISEASES ON SUBSEQUENT SQUASH W. S. Monfort, A. S. Csinos, A. R. Barrentine, and Lara Lee Hickman, University of Georgia- Department of Plant Pathology, P. O. Box 748, Tifton, GA 31793 Introduction Roundup Ultramax (glyphosate) and removed. Many plants in the Brassicaceae family Using the same treatment design from the produce glucosinolates naturally. previous crop, Vapam (metam sodium) was Glucosinolates degrade into compounds such as drip-applied at 50 gal/A in the wheat treatment methyl isothiocyanates (MITC) and allyl on 31 July prior to planting. Plastic covered isothiocyanates (AITC). plots were 25 feet long and 30 inches wide. Both MITC and AITC are lethal to Squash cv. “Prelude II”seedlings were soilborne pests such as nematodes and fungi. In purchased from Lewis Taylor Farms in Tifton. fact, the common fumigant metham sodium A single plant was transplanted using a degrades to MITC and then accounts for its mechanical type transplanter, which cuts holes activity as a soil fumigant. Since the Brassica in the in the plastic just ahead of the planters in species have been demonstrated to produce the center of the plastic bed adjacent to the drip glucosinolates which degrade into MITC and tape on 16 August. Plant spacing was 12 inches. AITC there is interest in determining if the All plots were injected with Admire (4oz/A on growing a Brassica crop prior to another crop 18 August) and sprayed with Phaser (1 Qt/A on susceptible to soilborne pests would benefit 25 August, and 5, 11, 18, and 25 September), from the rotation. This test evaluates the effect Pounce 3.2 (Permethrin) (8 oz/A on 16 of Brassica species grown prior to pepper. The October), Capture 2 EC (Bifenthrin) (5 oz/A on Brassica cover crop was planted in winter 2005 1, 6, 13, 20, 27 September and 6 and 10 followed by a planting of Tomato in spring 2006 October), and Intruder (Acetamiprid) (2 oz/A on and the subsequenst squash crop in fall 2006. 8, 15, 22, and 29 September) for insect control. Stand counts were done on 8 September Materials and Methods and vigor ratings were conducted on 20 The study was located at the Tifton September and 3 October. Plant vigor was rated Vegetable Park Farm, CPES, Tifton, GA. The on a scale of 1 to 10, 10 representing live and area has a history of assorted vegetable. The healthy plants and 1 representing dead plants. area was prepared using all current University of Twelve soil cores, 2.5-cm-diam H Georgia Extension Service recommendations. 25-cm-deep, were collected from the center of The test was a randomized complete block each plot at harvest of tomatoes (6 July), and at design consisting of single bed plots replicated planting (11 August) and harvest (31 October) four times. Each plot was 25 feet long and 6 feet of peppers. Nematodes were extracted from a wide with 5 foot alleys. 150-cm3 soil sub-sample using a centrifugal Brassica crops were radish (Scarlet sugar flotation technique. Soil fungal assays Globe), rapeseed (Dwarf Essex), rutabaga, and were conducted using a sub sample from the mustard (Florida Broadleaf). Other treatments collected soil. Aliquots of soil were removed were bare fallow and wheat with and without from each sub sample and air dried for 24 hours. Vapam. At the termination of the tomato crop, Five grams of dry soil were added to 100 ml of all tomato plants and weeds were killed with 0.3% water agar and mixed thoroughly. 36 Immediately afterward, 1 ml of soil/agar was test. Root-knot nematode soil populations were removed and mixed with 20 ml of 0.3% water highest in the radish, mustard, and control agar. One ml of the first preparation was fallow treatments at planting and at harvest of dispensed and spread evenly onto a petri plate squash. Root damage resulting from infection containing an oomycete-selective medium and feeding of root-knot was also highest in the (pimaricin-ampcillin-rifampicin-PCNB) for radish, mustard, and control fallow treatments isolation of Pythium species. One ml of the with the control fallow having the highest second preparation was dispensed and spread overall level of root damage compared to the onto a petri plate containing a Fusarium- other treatments. There were no significant selective medium (peptone-PCNB). Fungal differences noted in fungal populations in the plates were incubated for 120 hours for soil among the treatments although the radish Fusarium species and 48 hours for Pythium and rutabaga at plant of squash and radish, species. After incubation, CFUs were counted rutabaga, and rapeseed at harvest of squash had and recorded. the highest numeric populations of Pythium and On 31 October a root gall evaluation Fusarium in the soil than the other treatments. was conducted on three plants per plot using a 0 Affects of the Brassica and non- to 10 scale, whereby, 0 = no galls, 1 = very few Brassica treatments were also evaluated on small galls, 2 = numerous small galls, 3 = subsequent vegetable crop following tomato. numerous small galls of which some are grown The results indicated that the rapeseed, rutabaga, together, 4 = numerous small and some big and wheat with Vapam treatments had the galls, 5 = 25 % of roots severely galled, 6 = 50 highest yield in marketable number and weight % of roots severely galled, 7 =75 % of roots (numerically) with the control fallow and radish severely galled, 8 = no healthy roots but plant is treatment having the lowest yields in both still green, 9 = roots rotting and plant dying, 10 marketable fruit weight and number (Table 4). = plant and roots dead. Results for the evaluation of culled fruit showed All Tomato fruits were hand harvested that mustard, control fallow, radish, and wheat from the 10 foot center area of each bed. Each with Vapam treatments had the lowest number harvest was separated into marketable and cull and weight of culled fruit (Table 4). Results of fruits, counted and weighed. There were a total total fruit number and weight indicated that of four harvests, 2, 10, 17 and 26 October. rapeseed, rutabaga, and wheat with and without Vapam treatments had the highest number of Results and Summary fruit and fruit weight numerically compared to This test was conducted to evaluate the the other treatments with the lowest fruit number affects of Brassica and non-Brassica cover crop and weight being recorded in the control fallow treatments on subsequent crops in a double crop treatment (Table 4). vegetable system. Yellow squash was planted in The results of this test indicated that the fall following a spring tomato crop. There some cover crop treatments had a beneficial were few differences observed in plant stand affect on crop growth and yield. This increase counts among the cover crop treatments. in crop growth and yield might be the result of However, in evaluating plant vigor among the increased biomass and/or nutrients. The impact treatments radish, mustard, and control fallow of the Brassica and non-Brassica treatments treatments were found to significantly limit plant varied some between the treatments in the growth compared to the rutabaga treatments on subsequent crop as compared to the first 20 September and 3 October. The rutabaga vegetable crop on crop vigor and yield. Even treatments had also a numerically higher level of though there was an increase in nematode plant vigor than wheat treated with Vapam. populations and damage in some of the There was an increased level of root- treatments, the results are still questionable due knot nematode populations in the soil and root to the increased level of variability observed damage in the subsequent vegetable crop in this both among and with treatments. 37 38 39 40.