Therefore, substantial effort should be made to clean and disinfect all equipment used in a field with broomrape infestation. Equipment sanitation should begin with removal of plant and soil debris manually, as debris not only can contain seeds but can also reduce the effectiveness of disinfectants. Once most of the debris has been removed, chemical disinfection agents can be used on the equipment to kill any remaining seed and pathogens. According to Hershenhorn et al. , several quaternary ammonium products are available for disinfestation of farm equipment, such as didecyl dimethyl ammonium chloride, alkyl dimethyl benzyl ammonium chloride, dioctyl dimethyl ammonium chloride, octyl decyl dimethyl ammonium chloride, and ammonium bromide. Commercial products may contain one or a combination of these chemistries. For example, New Development Process is an example of a commercially available product, containing multiple quaternary ammonia, that can be used for disinfection of farm equipment, clothing and shoes against broomrape seeds. Soil fumigation using methyl bromide is one of the most effective tools to kill broomrape seeds, but due to its environmental toxicity the chemical has been banned and is no longer generally available. Even if methyl bromide were allowed under quarantine restrictions, the cost of treatment would be prohibitive. Other soil fumigants, such as chloropicrin, dazomet, metamsodium, metam-potassium and 1,3-dichloroproprene, may also provide different control levels of broomrape seeds . However, at this time, industrial drying rack few of these fumigants have been evaluated experimentally under California conditions.Herbicidal control of broomrape can be undertaken using pre-plant and post-plant herbicide applications and/or chemigation .

This is an area of on-going research in California and builds on programs developed in other regions. In processing tomato in Israel, for example, herbicides have been used to effectively and economically manage broomrapes in highly infested fields where eradication is no longer feasible . Growers found that pre-plant herbicide applications followed by complimentary post-transplant applications of acetolactate synthaseinhibiting herbicides such as sulfosulfuron provided control of Egyptian broomrape at both preand post-attached stages in tomato . The use of rimsulfuron as a pre-plant incorporated herbicide with a complimentary post-emergence application also provided good suppression of broomrape without causing significant damage to tomato plants . Some herbicide application protocols are based on the level of severity of broomrape infestation in tomato. For example, researchers in Israel have developed a thermal time-based decision support system named PICKIT that takes into account infestation levels and growing degree days since planting to guide the timing and rate of multiple herbicide applications for control of Egyptian broomrape; the system has been applied on a broad commercial scale . For severe infestations , growers apply sulfosulfuron three times post-planting at 200, 400 and 600 GDD, followed by overhead irrigation complemented by two foliar-applied doses of imazapic at a later growth stage. The DSS suggests that a medium level of broomrape infestation requires a single pre-plant incorporation of sulfosulfuron before planting tomato, followed by drip chemigation of imazapic at 400, 500, 600, 700 and 800 GDD, with two additional foliar imazapic applications at a later growth stage.

A similar DSS system is being tested on branched broomrape infestations in processing tomatoes in Chile and California with promising initial results .In California, only the rimsulfuron component of the PICKIT system is currently registered for use in processing tomato. Crop safety and registration support research is ongoing in California in an effort to register additional herbicides and application techniques in the event that branched and/or Egyptian broomrape problems expand in scale . A preliminary result from this research suggests that no visual injury and yield loss are associated with the use of the PICKIT system in local tomato fields .Cultural practice, such as rotating tomato plants with false hosts or non-host crops, could help with seedbank depletion, provided branched broomrape seed is not re-introduced to the field from outside. A trap crop is a species with root exudates that induce broomrape seed germination but the crop does not allow attachment or support broomrape seedling growth and survival. Potential trap crops for branched broomrape that can be used in a rotation are alfalfa , cowpea , green pea and flax . Tomato and other host crops should be excluded from the rotation for several years to encourage further depletion of seedbank with no chance of seed production. Since broomrape seed is very sensitive to flooding, incorporation of flooded rice into the crop rotation may also accelerate the depletion of soil seedbank . Soil fertility management can contribute substantially to the management of branched broomrape. Direct contact with fertilizer, such as urea and ammonium, may be toxic to broomrape, inhibiting seed germination and seedling growth . The negative effect of ammonium on broomrape is due to the plant’s limited ability to detoxify the ammonium compound using glutamine synthetase . Application of adequate fertilizer will not only ensure unhindered growth of the tomato plant; it will also minimize the release of the plant’s strigolactone, a root exudate that stimulates broomrape germination .

For example, it has been demonstrated that phosphate fertilization negatively impacts branched broomrape seed germination in tomato fields because of reductions in strigolactone exudation . Soil solarization has been shown to be an effective alternative to fumigation in reducing broomrape seed viability in areas with sufficiently hot climate. Solarization can significantly increase top soil temperatures up to 6 inches [15 cm] in depth when moist soil is covered with transparent polyethylene sheets for a period of one to two months. Dahlquist et al. reported 100% seed mortality of several weed species with solarization that raised soil temperature above 45°C for at least 96 cumulative hours. Mauro et al. found that soil solarization for two consecutive summers provided 99% mortality of viable seeds of branched broomrape in the seedbank without any negative impact on tomato yield. A recent field study conducted at UC Davis confirmed that soil solarization plus organic amends of either tomato pomace or plowed-down tomato plants can be used to substantially reduce the weed seedbank in general in tomato fields , although broomrape was not present at this site. One challenge in using this approach is the need to take tomato fields out of production for several months during the summer growing season in California. Additionally, it is not currently known if the elevated temperatures from solarization would penetrate deeply enough into the soil to provide adequate control of broomrape seed throughout the tomato root zone in an open-field production system. Other thermal methods of soil disinfestation, such as soil steaming, are another alternative to chemical fumigation. Soil steaming has been shown to be effective in controlling seeds of several weeds and other soil pest in California strawberry production . High soil temperatures of 158°F for 30 minutes can be regularly achieved in the field to a depth of 0 to 10 inches . This treatment seems to be sufficient to kill seeds of many weeds . Although the effect of this technique on broomrape seed mortality has not been studied, the small seed size of broomrape plants and their lack of protective tissues suggest that broomrape could be vulnerable to steam heating. However, like solarization, it is not known whether the depth of control from soil steaming would be sufficient as part of an eradication strategy for a quarantine pest like branched broomrape.Physical weed removal, such as hand weeding, particularly for a small infestation, can be part of an integrated approach to broomrape control. California is a state where hand removal of broomrape may be an option given the limited infestation level and widespread use of farm labor. The efficacy of hand weeding is highly dependent on thorough scouting and detection, drying rack for cannabis which can be very difficult given the plant’s small stature and the short period between its emergence and seed set . Deep inversion plowing would bury broomrape seeds to a depth below the soil layer where attachment to tomato root can occur . However, the dormancy and durability of broomrape seed in the soil seedbank would increase the risk of later broomrape re-occurrences. Physical removal and deep burial could be part of a management strategy if broomrape became too widespread for quarantine and eradication efforts to be feasible; however, because broomrape is an A-listed pest , physical removal and deep burial are not likely to provide a sufficient level of control alone.Biological control involves the use of biological agents or processes to damage seed, kill weedy plant or interfere with parasite-host relationships.

An insect herbivore, Phytomyza orobanchia, is known to be specific for broomrapes and feeds on broomrape ovules and seeds, thereby reducing broomrape seed production . Pathogens such as Fusarium sp. can be incorporated into the soil to control broomrape through an induced cytoplasm metabolism and endosperm cell wall degradation that breaks seed dormancy, thereby depleting the broomrape seedbank . Pathogen-based herbicides have been reportedly used to control young seedlings of parasitic weeds , and these bioherbicides can provide complete control of all emerged broomrapes if formulated with multiple pathogens . However, to date, no research on the applicability of these approaches in California cropping systems and broomrape infestation levels has been conducted, and they are not currently available for use. Cultivation of resistant tomato varieties would also be an effective approach to prevent parasitic effects of broomrape. Resistance to branched broomrape might be achieved by incorporating traits that prevent haustorium attachment and penetration, or tubercle formation; this approach has been demonstrated in broomrape-resistant sunflower . A group of scientists at UC Davis are currently screening a wide range of tomato varieties to determine their resistance to branched broomrape; results from this study could help to determine if enough genetic variability exists in tomato to use conventional breeding approaches to breed for broomrape resistance. Although screening is effective in small plots and is promising in the longer term, at present there are no effective commercial biological measures for broomrape control in tomato.The re-emergence and spread of branched broomrape are of great concern in tomato and other susceptible crop production systems in California. At this point in time, the problem is still relatively small. Current efforts are focused on quarantine and eradication using a regulatory approach and soil fumigation. These approaches depend on the reporting of new infestations and generally result in total crop loss to the grower and extremely high treatment costs. Therefore, success will depend on significant funding from state or industry sources to offset grower costs in order to ensure grower participation and reporting. In the event that broomrape problems in California expand beyond what can realistically be managed using quarantine approaches, management and mitigation approaches will be needed just like with other widespread weeds. Other countries have successfully demonstrated that an integrated approach on a long-term basis, involving outreach to growers, field scouting and detection of new infestations, mapping of contaminated areas and fields, equipment sanitation, manipulation of cultural practices and carefully timed herbicide treatments, among other treatments, can effectively reduce yield losses caused by branched broomrape. Significant research efforts are being made by a group of university, industry and regulatory scientists to develop detection and management approaches for branched broomrape and to modify existing approaches from other regions for adaptation in California.Across California, annual rangelands cover approximately 16 million acres and are among the most species-rich ecosystems in the state, supporting thousands of plant and animal species . California’s modern-day rangelands are largely dominated by nonnative annuals, which some believe replaced previously diverse native forb and grass communities . These naturalized annuals now provide a majority of the state’s livestock forage base. Currently, several noxious weed species are driving another transformation of California’s rangelands and pose a continued and growing threat to rangeland ecosystem functions and services . The spread of invasive weeds changes plant community composition and can lead to shifts in soil moisture and nutrient availability as well as the suppression of both native plants and other desirable and more palatable nonnatives, thereby reducing herbaceous diversity, wildlife habitat, forage quality and agricultural productivity . Across California’s annual rangelands, noxious weeds have been estimated to reduce livestock carrying capacity by as much as 50% to 80% .Two of the most prominent invasive species of concern are medusahead and yellow starthistle .