The cultural control method would be the only economically viable method for some crops in the developing country (Khoury and Makkouk, 2010). In order to reduce the incidence of P. capsici in chili, cultural practices such as raised beds, mulching, proper irrigation management, and moisture-based forecasting models would ensure reductions in the severity of the disease (Sanogo and Ji, 2013). In black pepper, phytosanitary measures would help reduce the primary inoculum and manage the foot rot disease. Shade regulation can be done to reduce humidity. The vines infected by foot rot symptoms will be uprooted and burnt earlier. Crop rotation with non-host species can be adopted to manage the field’s oospores (Babadoost, 2016). Adequate cultural practices favoring the plant and disfavoring the pathogen help reduce the disease severity. According to Granke et al. (2012), a slight angle of inclination of the beds in the rainy season is recommended for proper drainage. Khan et al. (2020) suggested phytosanitary measures such as removing and destroying affected parts and wound dressing with tar to manage the infection. Good drainage is the prime factor in minimizing Phytophthora in cinnamon crops. In oil palms, proper drainage and avoidance of overhead irrigation have reduced P. palmivora infections (Martínez, 2009). Covering the bunches with polythene effectively prevented foot rot disease in areca nut. Covering the bunches before the monsoon resulted in 100% control of this disease (Chowdappa et al., 2000). For the effective management of Phytophthora infection in cocoa plantations, cultural practices such as nutrient management, canopy pruning, and field hygiene were found to be highly successful (Peter and Chandramohan, 2014). As wet weather and excess moisture favor pathogen availability, ensuring adequate drainage prevents soil inoculum build-up. The selection of fields with low pathogen inoculum and good drainage is the first line of defense against this pathogen. Before chemical control methods, phytosanitary measures such as removing decayed materials, thinning, pruning, etc., were more efficacious in managing Phytophthora diseases.

Genetic resistance holds a pivotal role in plant disease management. Most cellular pathogens, such as fungi, bacteria, and oomycetes, use the effector and toxin proteins to enter the cytoplasm. In the case of oomycetes, they tend to enter the host cells directly (Tyler, 2011). P. capsici, being a pathogen with a broad host range, has developed resistance over time. Saltos et al. (2022) interpreted that some genotypes, such as Nathalie, ECU 12831, ECU 9129, and ECU 1296, showed effective resistance against root and crown rot diseases. Race-specific resistance (Sy et al., 2008) and Syndrome-specific resistance (Sy et al., 2005) has been reported in chili peppers. Using recurrent selection, has ensured polygenic resistance in the elite materials (Thabuis et al., 2004). Reeves et al. (2013) recognized a resistance gene (Ipcr) inhibiting P. capsici. Grafting was evident in conferring genetic resistance (Gisbert et al., 2010). Jang et al. (2012) reported that grafted pepper plants significantly resisted P. capsici and R. solanacearum. In chili crops, the genotypes were evaluated for resistance against P. capsici, which causes root rot. The evaluation concluded that a significant dominant gene associated with a few minor gene-controlled resistance. The genotype IHR 3575 was resistant against the virulent isolate PC-IIHR1 (Kumar et al., 2021). Mohammadbagheri et al. (2022) stated that, in characterizing the resistance for root and crown rot, the five new genotypes such as 11BlockyP-YToran, 19OrnP-PBI, 23CherryP-Orsh, 32OrnP-China, and 37ChilP-Paleo were found resistant against P. capsici. In Capsicum annum, 45 physiological races showing resistance using different R genes against Phytophthora root rot and blight were reported. McGregor et al. (2011) reported the various sources of resistance, such as Criollo de Morelos 334 (CM334), PI 201232, PI 201234, PI 201237, and PI 640532 from Mexico, followed by AC2258 from Central America, and perennial from India showing resistance to P. capsici. Piper colubrinum, a wild species of black pepper, was found resistant to P. capsici, causing rot diseases. The resistance is due to the hypersensitive response on recognition of the entry of the pathogen (Suraby et al., 2020).

Rachana et al. (2024) elucidated the use of coconut resistant gene analogues (CnRGAs) in formulating resistant breeding strategies against P. palmivora which causes bud rot in coconut. Cooley et al. (2000) identified the gene RPP8 to exhibit resistance against P. parasitica.

Similarly, the stacking of three resistant gene’s namely RB, Rpi-blb2, and Rpi-vnt1.1 proved highly successful in managing the late bight of potatoes which showed extreme resistance (Ghislain et al., 2019). The R genes including R1, R2, R3a, and R3b identified from the wild species of S.demissum exhibited race-specific resistance, aiding in the management of late blight disease in potato crops (Kim et al., 2012). The R8 gene found in the transgenic potatoes also tend to exhibit a broad spectral activity against P. infestans enabling long-term resistance (Jiang et al., 2018).

Similarily, The Rps11 gene provides resistance against P. sojae, serving as a promising source of resistance ensuring improved production and protection of soybean (Ping et al., 2016). The novelty of three resistance genes, namely Rps3a, Rps 3c, and Rps 4 was found to be effective in managing Phytophthora root rot in soybean crop (McCoy et al., 2022). So far, 33 Rps genes have been discovered in different soybean cultivars (Zhong et al., 2019) showing evident results in the management of Phytophthora root rot. Lucas (1975), reported the R genes Php and PhI to confer complete resistance to P. nicotianae otherwise known as race 0. Similarly, Drake et al. (2015) found the Wz gene to be highly effective in managing black shank disease caused by P. nicotianae. Mapping studies revealed the quantitative trait loci (QTL) Phn 7.1 to confer partial resistance against P.nicotianae. Future developments by combining both Ph and Wz genes in the genetic backgrounds could ensure slow adaptation to the pathogen, thereby contributing to improved cultivars, that are highly effective against black shank disease (Jin et al., 2022).

The resistance to black pod disease is primely oligogenic, and the genotypes of the F1 generation (TSH 1188 9 × CCN 51) could ensure increased resistance to black pod disease in future breeding programs (Barreto et al., 2015). Mucherino Muñoz et al. (2021) identified 20 QTL involved in resistance against Phytophthora species and suggested the involvement of the candidate genes 164 from CRIOLLO genome and 160 from the MATINA genome in the recognition and activation of defense responses. Baruah et al. (2024) studied the seven genotypes for their resistance to P. palmivora where the genotypes CCN51, Sca6, and Pound 7 exhibited resistance post-penetration which would ensure better management strategies against black pod rot disease of cocoa.

Apart from this, the usage of enzymes such as cellulose synthase 1, ATPases, mitogen-activated protein kinases, and Nep-1-like proteins, which tend to play an essential role in Phytophthora metabolism, can be employed for managing the pathogenesis of Phytophthora (Avila-Quezada and Rai, 2023).

For decades, fungicides have been essential in controlling plant diseases (Khoury and Makkouk, 2010). Chemicals are widely recommended for Phytophthora control, but their effectiveness varies depending on the incidence and severity, particularly during high-disease pressure in the wet season. At weekly intervals, copper-based fungicides and systemic fungicides such as metalaxyl are recommended for managing Phytophthora diseases. In black pepper, nursery treatment by spraying either with 1% Bordeaux mixture and soil drenching with 0.2% copper oxychloride or spray cum drenching with metalaxyl-mancozeb 0.125% or a spray with potassium phosphonate 0.3% at timely intervals is highly recommended to avoid the incidence and spread of Phytophthora species (Anandraj and Susheela Bhai, 2015; Kumar et al., 2012). For managing Phytophthora in cardamom through chemical means, spraying with 1% Bordeaux mixture or drenching with 0.2% copper oxychloride effectively destroyed the soil inoculum. Also, other chemicals like Fosetyl-aluminium 0.2% or potassium phosphonate can be sprayed @ 500-750 ml/clump. For effective management of Phytophthora species in Vanilla, spraying with 1% Bordeaux mixture and soil drenching with 0.25% copper oxychloride can be employed, depending on the disease severity. Spraying potassium phosphonate 0.4% was also effective in reducing the disease incidence. In tree species, spraying with 1% Bordeaux mixture before the onset of monsoon season effectively prevents disease development. The fungicidal application was found to be a prophylactic measure for managing Phytophthora diseases (Anandaraj and Suseela Bhai, 2015). Spraying of Bordeaux mixture (1%) and removing fallen nuts reduced the incidence of Phytophthora in areca nut. Naik et al. (2019) also found that applying a 1% Bordeaux mixture before the onset of monsoon drastically reduced the Koelroga disease in areca nut plantations. Sagaff et al. (2022) reported that using copper oxychloride mixed with mineral oil reduced the severity of abnormal leaf fall disease in rubber.

The application of fungicides had a better impact when used within an IDM strategy. New generation fungicides were eco-friendly, with minimal doses compared to conventional fungicides. Some of the new generation fungicides such as famoxadone, fenamidone, fluopicolide, zoxamide, iprovalicarb, benthiavalicarb, mandipropamid cyazofamid, and ethaboxam were found effective in managing Phytophthora species and other related oomycetes through various modes of action (Thind, 2009). Fluopicolide is a recently developed acyl picolide fungicide with a unique mode of action that is highly effective against a wide range of oomycetes. The study by (Shin et al., 2010) showed evident results in managing Phytophthora blight in pepper as fluopicolide served as a potent inhibitor of mycelial growth, zoospore release, and germination. Rini and Remya (2020) found that the new generation fungicide fenamidone 10WDG, along with mancozeb, resulted in the management of P. capsici in black pepper. Patil et al. (2023) evaluated the new generation fungicides against P. meadii in areca nut and concluded mandipropamid as an alternative control measure for fruit rot disease.

Phytophthora species infection poses considerable challenges to spice and plantation crop production globally. Traditional disease mitigation strategies, which often depend on chemical fungicides, are increasingly unsustainable due to environmental concerns and the development of resistance by pathogenic isolates. The alternative approach is to explore the effect of fungal and bacterial antagonists, which opens an avenue for Phytophthora management. Management of diseases using biological control agents (BCAs) seems to come from a combination of mechanisms, which includes the production of enzymes and antibiotics that play crucial roles in impeding the growth and progression of plant pathogens (Kumar et al., 2019). BCAs can suppress diseases in an eco-friendly and more sustainable manner (Yuliar et al., 2015). BCAs employ either direct or indirect methods to combat pathogenic organisms. Direct mechanisms involve actions like parasitism, antibiosis, or competition, while indirect mechanisms include inducing systemic resistance (Raymaekers et al., 2020). Biological control of plant diseases has evolved as a natural method of pathogen control by using beneficial microbes for sustainable crop production and protection (Avila-Quezada and Rai, 2023).

The usage of fungal BCAs has rapidly increased as they have higher reproductive rates and are more target-specific. They can survive as saprophytes in the absence of host plants (Thambugala et al., 2020). Among the fungal BCAs identified so far, Trichoderma species appears to be one of the effective BCAs as it has a broader range of action to the soil and foliar pathogens. Trichoderma is found to be a potent BCA as it uses complex modes of action such as parasitism, competition, production of antibiotics, and hyper-parasitism to combat pathogenic organisms (Mukhopadhyay and Kumar, 2020).

In black pepper, the fungal BCAs such as Trichoderma species and arbuscular mycorrhizal fungi were effective against foot rot disease. Vithya et al. (2018) reported that the CKT isolate of T. harzianum is a promising BCA-suppressing foot rot incidence. The secondary metabolites of the Trichoderma species inhibit the growth of pathogens. Coffee husk-based Trichoderma formulations have been reported effective in managing the foot rot of pepper. In betel vines, the combined applications of T. harzianum mixed with 500 kg oil cake applied at quarterly intervals were found effective against Phytophthora infection, and minimum incidence was observed (Dasgupta et al., 2011).

The native species of Trichoderma, such as T. harzianum and T. hamatum, exhibited greater antagonism against Phytophthora (de Ita et al., 2021). It was also reported that four isolates of Trichoderma species demonstrated antifungal activity and reduced the mycelial growth of the pathogen. In nutmeg crops, soil application of Trichoderma was practical (Sumbula and Mathew, 2015). The application of T. harzianum pellets @ a dosage of 2 g/100 ml suspension effectively inhibited the growth of Phytophthora in cocoa seedlings (Sriwati et al., 2019). The delayed occurrence and prevention were noticed in the cocoa plants by applying Trichoderma species. In areca nut, three native species of Trichoderma effectively controlled P. meadii under in vitro conditions. Among the species tested, T. virens showed maximum inhibition at 62.5%. The bioactive compounds from A. flavipes showed potent inhibitory activity against several species of Phytophthora (El-Sayed and Ali, 2020).

Bacteria play a pivotal role in the management of Phytophthora (Avila-Quezada and Rai, 2023). Bacterial BCAs have gained importance as they are effective against various fungal and bacterial pathogens that cause damage to crops worldwide. The bacterial BCAs use various modes of action, which can be classified into direct and indirect, to suppress the growth of pathogens. The bacterial BCAs use different mechanisms such as antibiosis, siderophore production, competition for space and nutrition, parasitism, biofilm formation, and induction of host resistance to combat the fungal and bacterial pathogens (Haidar et al., 2016). The volatile organic compounds produced by the bacterial agents play significant roles in host plant interactions (De Vrieze et al., 2015). For example, the bacterial strains NH7, NH27, NH32 and NH46 identified as Enterobacter cloacae, Streptomyces flaveus, Klebsiella pneumoniae, and Bacillus amyloliquefaciens exhibited strong antagonistic activity against P. capsici along with the production of chitinolytic enzymes aiding in successful disease management (Nguyen et al., 2022).

In chili crop, the rhizosphere organisms was isolated and tested for their antagonism. Among the 15 isolates obtained, eight were found to be potential. The strains were tested under greenhouse conditions, showing significant disease suppression against P. capsici with increased plant growth characteristics (Hyder et al., 2020). In pepper, the bacterial isolates obtained from the rhizosphere, phyllosphere, and endosphere showed maximum ability to reduce the disease severity. The biocontrol efficacy tested ranged from 0.7% to 92.3%. The bacterial BCA, such as Bacillus cereus and Chrysobacterium species, helped manage Phytophthora blight (Yang et al., 2012). Trihn et al. (2019) screened the bacterial BCA, Bacillus velezensis RB.DS29 to exhibit strong antifungal activities against Phytophthora along with plant growth promotion in black pepper. Similarly, the bacterial agents including B. cereus, B. polymyxa, and B.licheniformis emerged as potential BCAs in managing P. meadii causing fruit rot of arecanut (Shalini and Rajashekhar, 2006). In cardamom, the two bacterial strains Pseudomonas fluorescens (Pf 51) and Bacillus subtilis (Bs) showed more significant levels of inhibition, such as 40.2% and 39.7% against P. meadii (Sivakumar et al., 2015) also reported the compatible nature of P. fluorescens and B. subtilis and concluded the effectiveness in disease suppression.

Latha et al. (2023) emphasized that soil and crown applications of B. subtilis @10 g/l of water, applied at two intervals, effectively reduced the incidence of Phytophthora in coconut. The bacterial agent Pseudomonas fluoresecnes showed evident results against P. palmivora under in vitro and could aid in better disease management (Aruna and Motha, 2020). Thomas et al. (2011) identified 44 Bacillus species from the rhizospheric region and six Pseudomonas species from the rhizosphere that exhibited antagonistic activity against P. palmivora, making them potential bacterial BCAs. Similarily, the bacterial BCA, Paenibacillus polymyxa NMA1017 exhibited significant effectiveness in managing P. tropicalis causing black pod rot of cocoa, establishing it as potential BCA (Chávez-Ramírez et al., 2021; Wu et al., 2015) reported that compounds such as volatiles, siderophores produced by the bacteria, flagellin, and lipopeptides tend to engender induced systemic resistance against some fungal species.

The endophytic bacteria obtained from the roots, stem, and leaves of the wild relative of black pepper Piper colubrinum was found effective and resistant against P. capsici. The growth was significant when the cuttings were bacterized (Irabor and Mmbaga, 2017; Kollakkodan et al., 2021) stated that endophytic bacteria, such as Bacillus species, were effective in controlling P. capsici and promoting bell pepper plant growth (Adama et al., 2020) stated that the cocoa tree naturally has endophytic bacteria, which can be used as potential antagonists against P. palmivora and P. megakarya. The bacterial endophytic isolates obtained from the healthy parts of the cocoa plant were screened for their antagonistic activity under in vitro conditions where P. aeruginosa and C. proteolyticum showed 100% inhibition against P. palmivora (Alsultan et al., 2019).

The antagonistic potential of bacterial endophytes against P. meadii was screened under in vitro conditions wherein six isolates were found virulent, among which EIL-2 showed maximum inhibition of 62.5% (Abraham et al., 2013). It was reported that the antagonism displayed against P. meadii may be used to control Phytophthora disease in vivo. The fungal endophytic Trichoderma strains were tested for their potential antagonism and efficacy where the strains of T. harzianum KUFA0436 and KUFA037 showed disease suppression by 43% and 48% (Sirikamonsathien et al., 2023). Dang et al. (2023) identified the endophytic isolates including Penicillium citrinium, Xylaria curta, and Clonostachys rosea to pose strong antagonistic activities against Phytophthora spp. which could serve as effective BCA against root rot disease in cinnamon.

Despite the limited availability of BCAs, the fungal BCA such as Trichoderma species and the bacterial agents such as Bacillus species and Pseudomonas species have been proven effective in managing Phytophthora in spice and plantation crops by various researchers. The development of microbial consortia of T. harzianum, P. fluorescens, and B. megaterium reduced the severity of the disease along with the overall growth and development of palms (Naik et al., 2019).

In cardamom plants, the combined application of antagonistic organisms through rhizome and soil treatments reduced the capsule infection by 60% (Sivakumar et al., 2012). For managing foot rot of black pepper, combined applications of T. asperellum, P. fluorescens, and AMF are recommended when planting in the nursery and main field. The combination of BCAs has proven to be very effective against the growth and development of Phytophthora species because of the synergistic activities of the antagonists, which enhances their efficacy (Manasfi et al., 2018).

The combined applications of neem cake amended with Trichoderma 1 kg/vine showed increased microflora populations and reduced root infections. In nutmeg, the combination of treatments, such as a spray with 1% Bordeaux mixture and soil application with T. viride, showed progressive results in disease reduction (Sumbula and Mathew, 2015). The combined applications of potassium phosphonate with T. harzianum reduced foot rot incidence in black pepper. Since the actual disease of small cardamom solely depends on weather parameters, an IDM strategy involving plant sanitation, such as removal of diseased plant parts and shade regulation before the onset of monsoon, followed by chemical and biological methods such as the application of prophylactic fungicidal spray and soil application of Trichoderma species before the rainy season would be more helpful in managing this disease (Thomas and Suseela, 1995).

In cinnamon crops, the combination of cultural practices such as removal and destruction of the infected plant parts, shade lopping to ensure sunlight, availing proper drainage followed by chemical control measures viz., spraying of 1% Bordeaux mixture and soil drenching with copper oxychloride 0.25% reduced the incidence and spread of disease. In tree species, phytosanitary measures such as removing the infected and fallen nuts along with a prophylactic spray of 1% Bordeaux mixture help prevent the disease’s survival and spread (Anandaraj and Susheel Bhai, 2015). For managing black pod disease in cocoa, applying copper oxychloride followed by metalaxyl + mancozeb and suitable cultural practices showed good, reliable results in disease control (Peter and Chandramohan, 2014). Application of lime @ 200 kg/ha during pre-monsoon season followed by the application of 1% Bordeaux mixture as a foliar spray with suitable cultural practices such as removal of fallen nuts, ensuring proper drainage, and removal of excessive branches in the intercrops showed evident results in managing Phytophthora in areca nut fields (Balanagouda et al., 2021). The ultimate goal of IDM lies in achieving both efficient disease control and the mitigation of plant diseases, along with minimizing detrimental effects.